diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersValidator.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersValidator.java
index 866a2e7..8f2b262 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersValidator.java
@@ -51,8 +51,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 import org.eclipse.jgit.diff.RawText;
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
@@ -230,17 +228,6 @@
     }
   }
 
-  // Line patterns accepted by Parser.java in the find-owners plugin.
-  static final Pattern patComment = Pattern.compile("^ *(#.*)?$");
-  static final Pattern patEmail = // email address or a "*"
-      Pattern.compile("^ *([^ <>@]+@[^ <>@#]+|\\*) *(#.*)?$");
-  static final Pattern patFile = Pattern.compile("^ *file:.*$");
-  static final Pattern patNoParent = Pattern.compile("^ *set +noparent *(#.*)?$");
-  static final Pattern patPerFileNoParent =
-      Pattern.compile("^ *per-file +([^= ]+) *= *set +noparent *(#.*)?$");
-  static final Pattern patPerFileEmail =
-      Pattern.compile("^ *per-file +([^= ]+) *= *([^ <>@]+@[^ <>@#]+|\\*) *(#.*)?$");
-
   private static void collectEmail(
       Map<String, Set<String>> map, String email, String file, int lineNumber) {
     if (!email.equals("*")) {
@@ -268,17 +255,18 @@
       String path,
       int lineNumber,
       String line) {
-    Matcher m;
-    if (patComment.matcher(line).find()
-        || patNoParent.matcher(line).find()
-        || patPerFileNoParent.matcher(line).find()) {
-      return;
-    } else if ((m = patEmail.matcher(line)).find()) {
-      collectEmail(email2lines, m.group(1), path, lineNumber);
-    } else if ((m = patPerFileEmail.matcher(line)).find()) {
-      collectEmail(email2lines, m.group(2).trim(), path, lineNumber);
+    String email;
+    String[] emails;
+    if (Parser.isComment(line) || Parser.isNoParent(line)) {
+      // no email address to check
+    } else if ((email = Parser.parseEmail(line)) != null) {
+      collectEmail(email2lines, email, path, lineNumber);
+    } else if ((emails = Parser.parsePerFileEmails(line)) != null) {
+      for (String e : emails) {
+        collectEmail(email2lines, e, path, lineNumber);
+      }
     } else {
-      String prefix = patFile.matcher(line).find() ? "ignored" : "syntax";
+      String prefix = Parser.isFile(line) ? "ignored" : "syntax";
       add(messages, prefix + ": " + path + ":" + lineNumber + ": " + line, true);
     }
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Parser.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Parser.java
index 57f137d..1264e78 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Parser.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Parser.java
@@ -28,31 +28,90 @@
  * <p>OWNERS file syntax:
  *
  * <pre>
- * lines     := (\s* line? \s* "\n")*
- * line      := "set noparent"
- *           | "per-file" \s+ glob \s* "=" \s* directive
- *           | "file:" glob
- *           | comment
- *           | directive
- * directive := email_address
- *           |  "*"
- * glob      := [a-zA-Z0-9_-*?]+
- * comment   := "#" [^"\n"]*
+ * lines      := (\s* line? \s* "\n")*
+ * line       := "set" \s+ "noparent"
+ *            | "per-file" \s+ globs \s* "=" \s* directives
+ *            | "file:" \s* glob
+ *            | comment
+ *            | directive
+ * directives := directive (comma directive)*
+ * directive  := email_address
+ *            |  "*"
+ * globs      := glob (comma glob)*
+ * glob       := [a-zA-Z0-9_-*?.]+
+ * comma      := \s* "," \s*
+ * comment    := "#" [^"\n"]*
  * </pre>
  *
  * <p>The "file:" directive is not implemented yet.
  *
- * <p>"per-file glob = directive" applies directive only to files matching glob. glob does not
- * contain directory path.
+ * <p>"per-file globs = directives" applies each directive to files matching any of the globs.
+ * A glob does not contain directory path.
  */
 class Parser {
-  static final Pattern patComment = Pattern.compile("^ *(#.*)?$");
+  // Globs and emails are separated by commas with optional spaces around a comma.
+  protected static final String COMMA = "[\\s]*,[\\s]*"; // used in unit tests
+
+  private static final String  BOL = "^[\\s]*";          // begin-of-line
+  private static final String  EOL = "[\\s]*(#.*)?$";    // end-of-line
+  private static final String  GLOB = "[^\\s,=]+";       // a file glob
+
   // TODO: have a more precise email address pattern.
-  static final Pattern patEmail = // email address or a "*"
-      Pattern.compile("^ *([^ <>@]+@[^ <>@#]+|\\*) *(#.*)?$");
-  static final Pattern patFile = Pattern.compile("^ *file:.*$");
-  static final Pattern patNoParent = Pattern.compile("^ *set +noparent(( |#).*)?$");
-  static final Pattern patPerFile = Pattern.compile("^ *per-file +([^= ]+) *= *([^#]+).*$");
+  private static final String  EMAIL_OR_STAR = "([^\\s<>@,]+@[^\\s<>@#,]+|\\*)";
+
+  // Simple input lines with 0 or 1 sub-pattern.
+  private static final Pattern patComment = Pattern.compile(BOL + EOL);
+  private static final Pattern patEmail = Pattern.compile(BOL + EMAIL_OR_STAR + EOL);
+  private static final Pattern patFile = Pattern.compile(BOL + "file:.*" + EOL);
+  private static final Pattern patNoParent = Pattern.compile(BOL + "set[\\s]+noparent" + EOL);
+
+  // Patterns to match trimmed globs and emails in per-file lines.
+  private static final Pattern patEmailList =
+      Pattern.compile("^(" + EMAIL_OR_STAR + "(" + COMMA + EMAIL_OR_STAR + ")*)$");
+  private static final Pattern patGlobs =
+      Pattern.compile("^(" + GLOB + "(" + COMMA + GLOB + ")*)$");
+  // patPerFile matches a line to two groups: (1) globs, (2) emails
+  // Trimmed 1st group should match patGlobs; trimmed 2nd group should match patEmailList.
+  private static final Pattern patPerFile =
+      Pattern.compile(BOL + "per-file[\\s]+([^=#]+)=[\\s]*([^#]+)" + EOL);
+
+  static boolean isComment(String line) {
+    return patComment.matcher(line).matches();
+  }
+
+  static boolean isFile(String line) {
+    return patFile.matcher(line).matches();
+  }
+
+  static boolean isGlobs(String line) {
+    return patGlobs.matcher(line).matches();
+  }
+
+  static boolean isNoParent(String line) {
+    return patNoParent.matcher(line).matches();
+  }
+
+  static String parseEmail(String line) {
+    Matcher m = Parser.patEmail.matcher(line);
+    return m.matches() ? m.group(1).trim() : null;
+  }
+
+  static String[] parsePerFile(String line) {
+    Matcher m = patPerFile.matcher(line);
+    if (!m.matches() || !isGlobs(m.group(1).trim())
+        || !patEmailList.matcher(m.group(2).trim()).matches()) {
+      return null;
+    }
+    String[] parts = new String[2];
+    parts[0] = m.group(1).trim();
+    parts[1] = m.group(2).trim();
+    return parts;
+  }
+
+  static String[] parsePerFileEmails(String line) {
+    String[] globsAndEmails = parsePerFile(line);
+    return (globsAndEmails != null) ? globsAndEmails[1].split(COMMA) : null;
+  }
 
   static class Result {
     boolean stopLooking; // if this file contains set noparent
@@ -88,28 +147,23 @@
    */
   static void parseLine(Result result, String dir, String file, String line, int num) {
     // comment and file: directive are parsed but ignored.
-    if (patNoParent.matcher(line).find()) {
+    String email;
+    String[] globsAndEmails;
+    if (isNoParent(line)) {
       result.stopLooking = true;
-    } else if (patPerFile.matcher(line).find()) {
-      Matcher m = patPerFile.matcher(line);
-      m.find();
-      parseDirective(result, dir + m.group(1), file, m.group(2).trim(), num);
-    } else if (patFile.matcher(line).find()) {
-      result.warnings.add(warningMsg(file, num, "ignored", line));
-    } else if (patComment.matcher(line).find()) {
+    } else if (isComment(line)) {
       // ignore comment and empty lines.
-    } else {
-      parseDirective(result, dir, file, line, num);
-    }
-  }
-
-  private static void parseDirective(
-      Result result, String pathGlob, String file, String line, int num) {
-    // A directive is an email address or "*".
-    if (patEmail.matcher(line).find()) {
-      Matcher m = patEmail.matcher(line);
-      m.find();
-      Util.addToMap(result.owner2paths, m.group(1), pathGlob);
+    } else if ((email = parseEmail(line)) != null) {
+      Util.addToMap(result.owner2paths, email, dir);
+    } else if ((globsAndEmails = parsePerFile(line)) != null) {
+      String[] emails = globsAndEmails[1].split(COMMA);
+      for (String glob : globsAndEmails[0].split(COMMA)) {
+        for (String e : emails) {
+          Util.addToMap(result.owner2paths, e, dir + glob);
+        }
+      }
+    } else if (isFile(line)) {
+      result.warnings.add(warningMsg(file, num, "ignored", line));
     } else {
       result.errors.add(errorMsg(file, num, "ignored unknown line", line));
     }
diff --git a/src/main/resources/Documentation/syntax.md b/src/main/resources/Documentation/syntax.md
index 54db99f..0cf3ae7 100644
--- a/src/main/resources/Documentation/syntax.md
+++ b/src/main/resources/Documentation/syntax.md
@@ -7,23 +7,27 @@
 The syntax is:
 
 ```java
-lines     := (SPACE* line? SPACE* EOL)*
-line      := "set noparent"
-          |  "per-file" SPACE+ glob SPACE* "=" SPACE* directive
-          |  comment
-          |  directive
-directive := email
-          |  "*"
-glob      := [a-zA-Z0-9_-*?]+
-comment   := "#" ANYCHAR*
-email     := [^ @]+@[^ #]+
-ANYCHAR   := any character but EOL
-EOL       := end of line characters
-SPACE     := any white space character
+lines      := (SPACE* line? SPACE* EOL)*
+line       := "set" SPACE+ "noparent"
+           |  "per-file" SPACE+ globs SPACE* "=" SPACE* directives
+           |  comment
+           |  directive
+directives := directive (SPACE* "," SPACE* directive)*
+directive  := email
+           |  "*"
+globs      := glob (SPACE* "," SPACE* glob)*
+glob       := [a-zA-Z0-9_-*?.]+
+comment    := "#" ANYCHAR*
+email      := [^ @]+@[^ #]+
+ANYCHAR    := any character but EOL
+EOL        := end of line characters
+SPACE      := any white space character
 ```
 
-* `per-file glob = directive` applies `directive` only to files
-  matching `glob`, which does not contain directory path.
+* `per-file globs = directives` applies each `directive` only to files
+  matching any of the `glob`.
+
+* A 'glob' does not contain directory path.
 
 * The email addresses should belong to registered Gerrit users.
 
diff --git a/src/test/java/com/googlesource/gerrit/plugins/findowners/OwnersValidatorTest.java b/src/test/java/com/googlesource/gerrit/plugins/findowners/OwnersValidatorTest.java
index b8d445a..3403bcc 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/findowners/OwnersValidatorTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/findowners/OwnersValidatorTest.java
@@ -135,17 +135,18 @@
               + "   user1@google.com # comment\n"
               + "u1+review@g.com###\n"
               + " * # everyone can approve\n"
-              + "per-file *.py =  set  noparent###\n"
-              + "per-file   *.py=u2.m@g.com\n"
-              + "per-file *.txt = * # everyone can approve\n"
-              + "set  noparent  # comment\n");
+              + "per-file   *.py=u2.m@g.com   \n"
+              + "per-file *.c, *.java ,A*bp = u1@g.com, u1+review@g.com  ,u2.m@g.com#comment\n"
+              + "  per-file *.txt = * # everyone can approve #  \n"
+              + "  set   noparent  # comment#\n");
 
   private static final ImmutableSet<String> EXPECTED_VERBOSE_OUTPUT =
       ImmutableSet.of(
           "MSG: validate: " + OWNERS,
-          "MSG: owner: user1@google.com",
           "MSG: owner: u1+review@g.com",
-          "MSG: owner: u2.m@g.com");
+          "MSG: owner: u1@g.com",
+          "MSG: owner: u2.m@g.com",
+          "MSG: owner: user1@google.com");
 
   @Test
   public void testGoodInput() throws Exception {
diff --git a/src/test/java/com/googlesource/gerrit/plugins/findowners/ParserTest.java b/src/test/java/com/googlesource/gerrit/plugins/findowners/ParserTest.java
index 6f0ca72..bd50f0a 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/findowners/ParserTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/findowners/ParserTest.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import java.util.Arrays;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -119,27 +120,40 @@
 
   @Test
   public void perFileGoodDirectiveTest() {
-    String[] directives = {"abc@google.com#comment", "  *# comment", "  xyz@gmail.com # comment"};
-    String[] emails = {"abc@google.com", "*", "xyz@gmail.com"};
+    String[] directives = {
+      "abc@google.com#comment", "  *# comment", "  xyz@gmail.com # comment",
+      "a@g.com  ,  xyz@gmail.com , *  # comment", "*,*#comment", "  a@b,c@d  "
+    };
+    String[] globsList = {"*", "*,*.c", "  *test*.java , *.cc, *.cpp  ", "*.bp,*.mk ,A*  "};
     for (int i = 0; i < directives.length; i++) {
-      String line = "per-file *test*.java=" + directives[i];
-      Parser.Result result = testLine(line);
-      String[] paths = result.owner2paths.get(emails[i]).toArray(new String[1]);
-      assertThat(paths.length).isEqualTo(1);
-      assertThat(paths[0]).isEqualTo(mockedTestDir() + "*test*.java");
+      for (String globs : globsList) {
+        String line = "per-file " + globs + "=" + directives[i];
+        Parser.Result result = testLine(line);
+        String[] emailList = directives[i].replaceAll("#.*$", "").trim().split(Parser.COMMA);
+        String[] globList = globs.trim().split(Parser.COMMA);
+        Arrays.sort(globList);
+        for (String email : emailList) {
+          String[] paths = result.owner2paths.get(email).toArray(new String[1]);
+          assertThat(paths.length).isEqualTo(globList.length);
+          Arrays.sort(paths);
+          for (int g = 0; g < globList.length; g++) {
+            assertThat(paths[g]).isEqualTo(mockedTestDir() + globList[g]);
+          }
+        }
+      }
     }
   }
 
   @Test
   public void perFileBadDirectiveTest() {
     String[] directives = {
-      "file://OWNERS", " ** ", "a b@c .co", "a@b@c  #com", "a.<b>@zc#", " set  noparent "
+      "file://OWNERS", " ** ", "a b@c .co", "a@b@c  #com", "a.<b>@zc#", " set  noparent ",
+      " , a@b  ", "a@b, , c@d  #"
     };
-    String[] errors = {"file://OWNERS", "**", "a b@c .co", "a@b@c", "a.<b>@zc", "set  noparent"};
     for (int i = 0; i < directives.length; i++) {
       String line = "per-file *test*.c=" + directives[i];
       Parser.Result result = testLine(line);
-      String expected = testLineErrorMsg(errors[i]);
+      String expected = testLineErrorMsg(line);
       assertThat(result.warnings).isEmpty();
       assertThat(result.errors).hasSize(1);
       assertThat(result.errors.get(0)).isEqualTo(expected);