diff --git a/README.md b/README.md
index 4579db6..1cbe350 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,21 @@ mime.lookup('folder/.htaccess') // false
 mime.lookup('cats') // false
 ```
 
+### mime.lookupAll(path)
+
+Find all MIME type associated with a file.
+
+```js
+mime.lookupAll('json')             // ['application/json']
+mime.lookupAll('.rtf')             // ['application/rtf', 'text/rtf']
+mime.lookupAll('file.bmp')         // ['image/bmp', 'image/x-ms-bmp']
+mime.lookupAll('folder/file.js')   // ['application/javascript']
+mime.lookupAll('folder/.htaccess') // []
+
+mime.lookupAll('cats')             // []
+mime.lookupAll(42)                 // false
+```
+
 ### mime.contentType(type)
 
 Create a full content-type header given a content-type or extension.
diff --git a/index.js b/index.js
index 6e0ea43..ca91454 100644
--- a/index.js
+++ b/index.js
@@ -22,6 +22,7 @@ var extname = require('path').extname
 
 var extractTypeRegExp = /^\s*([^;\s]*)(?:;|\s|$)/
 var textTypeRegExp = /^text\//i
+var typeSets = {}
 
 /**
  * Module exports.
@@ -34,11 +35,15 @@ exports.contentType = contentType
 exports.extension = extension
 exports.extensions = Object.create(null)
 exports.lookup = lookup
+exports.lookupAll = lookupAll
 exports.types = Object.create(null)
 
 // Populate the extensions/types maps
 populateMaps(exports.extensions, exports.types)
 
+// Populate the extensions->[types] set
+populateTypeSets(typeSets)
+
 /**
  * Get the default charset for a MIME type.
  *
@@ -123,13 +128,16 @@ function extension (type) {
 }
 
 /**
- * Lookup the MIME type for a file path/extension.
+ * Obtain the extension of a filename or filepath.
+ * If the path is not a string or a proper extension isn't found,
+ *   false is returned.
+ * The path is case insensitive (so hello.html and HELLO.HTML are equal).
  *
  * @param {string} path
- * @return {boolean|string}
+ * @return {boolean|string} the file extension if available. false otherwise.
  */
 
-function lookup (path) {
+function extractExtension (path) {
   if (!path || typeof path !== 'string') {
     return false
   }
@@ -143,9 +151,43 @@ function lookup (path) {
     return false
   }
 
+  return extension
+}
+
+/**
+ * Lookup the MIME type for a file path/extension.
+ *
+ * @param {string} path
+ * @return {boolean|string}
+ */
+
+function lookup (path) {
+  var extension = extractExtension(path)
+
+  if (!extension) {
+    return false
+  }
+
   return exports.types[extension] || false
 }
 
+/**
+ * Find all MIME types that are associated with a file extensions.
+ *
+ * @param {string} path or file extension
+ * @return {boolean|array<string>}
+ */
+
+function lookupAll (path) {
+  var extension = extractExtension(path)
+
+  if (!extension) {
+    return false
+  }
+
+  return typeSets[extension] || []
+}
+
 /**
  * Populate the extensions and types maps.
  * @private
@@ -186,3 +228,29 @@ function populateMaps (extensions, types) {
     }
   })
 }
+
+/**
+ * Populate the set where extension->[types]
+ * An example is .rtf -> ['application/rtf', 'text/rtf']
+ *
+ * @private
+ * @param {object<string, array<string>>} the map to fill in
+ */
+
+function populateTypeSets (typeSets) {
+  Object.keys(db).forEach(function (type) {
+    var exts = db[type].extensions
+
+    if (!exts || !exts.length) {
+      return
+    }
+
+    exts.forEach(function (ext) {
+      if (typeSets[ext]) {
+        typeSets[ext].push(type)
+      } else {
+        typeSets[ext] = [type]
+      }
+    })
+  })
+}
diff --git a/test/test.js b/test/test.js
index 472cbcc..b30af35 100644
--- a/test/test.js
+++ b/test/test.js
@@ -2,6 +2,12 @@
 var assert = require('assert')
 var mimeTypes = require('..')
 
+var allMatch = function (actual, expected) {
+  expected.forEach(function (expectedType) {
+    assert.ok(actual.indexOf(expectedType) > -1)
+  })
+}
+
 describe('mimeTypes', function () {
   describe('.charset(type)', function () {
     it('should return "UTF-8" for "application/json"', function () {
@@ -224,4 +230,77 @@ describe('mimeTypes', function () {
       })
     })
   })
+
+  describe('.lookupAll(extension)', function () {
+    it('should return a list with multiple mime types when many exist', function () {
+      allMatch(mimeTypes.lookupAll('.rtf'), ['application/rtf', 'text/rtf'])
+    })
+
+    it('should return a list with one mime type when only one exists', function () {
+      allMatch(mimeTypes.lookupAll('.html'), ['text/html'])
+    })
+
+    it('should work without a leading dot', function () {
+      allMatch(mimeTypes.lookupAll('rtf'), ['application/rtf', 'text/rtf'])
+    })
+
+    it('should be case-insensitive', function () {
+      allMatch(mimeTypes.lookupAll('RtF'), ['application/rtf', 'text/rtf'])
+      allMatch(mimeTypes.lookupAll('.HTML'), ['text/html'])
+    })
+
+    it('should return an empty list for an unknown extension', function () {
+      allMatch(mimeTypes.lookupAll('bogus'), [])
+    })
+
+    it('should return false for non-strings', function () {
+      assert.strictEqual(mimeTypes.lookupAll(null), false)
+      assert.strictEqual(mimeTypes.lookupAll(undefined), false)
+      assert.strictEqual(mimeTypes.lookupAll(3.141592), false)
+      assert.strictEqual(mimeTypes.lookupAll({}), false)
+    })
+  })
+
+  describe('.lookupAll(path)', function () {
+    it('should return mime type for file name', function () {
+      allMatch(mimeTypes.lookupAll('page.html'), ['text/html'])
+    })
+
+    it('should return mime type for relative path', function () {
+      allMatch(mimeTypes.lookupAll('path/to/page.html'), ['text/html'])
+      allMatch(mimeTypes.lookupAll('path\\to\\doc.rtf'), ['application/rtf', 'text/rtf'])
+    })
+
+    it('should return mime type for absolute path', function () {
+      allMatch(mimeTypes.lookupAll('/path/to/page.html'), ['text/html'])
+      allMatch(mimeTypes.lookupAll('C:\\path\\to\\doc.rtf'), ['application/rtf', 'text/rtf'])
+    })
+
+    it('should be case insensitive', function () {
+      allMatch(mimeTypes.lookupAll('/path/to/PAGE.HTML'), ['text/html'])
+      allMatch(mimeTypes.lookupAll('C:\\path\\to\\DOC.RTF'), ['application/rtf', 'text/rtf'])
+    })
+
+    it('should return an empty list for unknown extension', function () {
+      allMatch(mimeTypes.lookupAll('/path/to/file.bogus'), [])
+    })
+
+    it('should return false for path without extension', function () {
+      assert.strictEqual(mimeTypes.lookupAll('/path/to/json'), false)
+    })
+
+    describe('lookupAll() - path with dotfile', function () {
+      it('should return false when extension-less', function () {
+        assert.strictEqual(mimeTypes.lookupAll('/path/to/.json'), false)
+      })
+
+      it('should return all mime types when there is extension', function () {
+        allMatch(mimeTypes.lookupAll('/path/to/.config.json'), ['application/json'])
+      })
+
+      it('should return all mime types when there is extension, but no path', function () {
+        allMatch(mimeTypes.lookupAll('.config.json'), ['application/json'])
+      })
+    })
+  })
 })