diff --git misc/autocomplete.js misc/autocomplete.js
index d66054b..5dbb58c 100644
--- misc/autocomplete.js
+++ misc/autocomplete.js
@@ -291,7 +291,7 @@ Drupal.ACDB.prototype.search = function (searchString) {
     // Ajax GET request for autocompletion.
     $.ajax({
       type: 'GET',
-      url: db.uri + '/' + encodeURIComponent(searchString),
+      url: db.uri + '/' + Drupal.encodePath(searchString),
       dataType: 'json',
       success: function (matches) {
         if (typeof matches.status == 'undefined' || matches.status != 0) {
diff --git modules/taxonomy/taxonomy.module modules/taxonomy/taxonomy.module
index 6cacb25..a7e4f30 100644
--- modules/taxonomy/taxonomy.module
+++ modules/taxonomy/taxonomy.module
@@ -313,6 +313,18 @@ function taxonomy_menu() {
     'type' => MENU_CALLBACK,
     'file' => 'taxonomy.pages.inc',
   );
+  $items['taxonomy/autocomplete/%/%menu_tail'] = array(
+    'title' => 'Autocomplete taxonomy',
+    'page callback' => 'taxonomy_autocomplete',
+    'page arguments' => array(2, 3),
+    'access arguments' => array('access content'),
+    'type' => MENU_CALLBACK,
+    'file' => 'taxonomy.pages.inc',
+    // Needed for menu_tail_load().
+    'load arguments' => array('%map', '%index'),
+  );
+  // This is needed because the autocomplete system relies on this path existing.
+  // See: http://drupal.org/node/93854
   $items['taxonomy/autocomplete'] = array(
     'title' => 'Autocomplete taxonomy',
     'page callback' => 'taxonomy_autocomplete',
diff --git modules/taxonomy/taxonomy.test modules/taxonomy/taxonomy.test
index 0664c52..8385d09 100644
--- modules/taxonomy/taxonomy.test
+++ modules/taxonomy/taxonomy.test
@@ -601,6 +601,27 @@ class TaxonomyTermTestCase extends TaxonomyWebTestCase {
   }
 
   /**
+   * Test term autocompletion edge cases.
+   */
+  function testTermAutocompletion() {
+    $base = $this->randomName(2);
+    // Add a term with a slash in the name.
+    $term = $this->createTerm($this->vocabulary);
+    $term->name = $base . '/' . $this->randomName();
+    taxonomy_term_save($term);
+    // Add a term with a slash in the name.
+    $term = $this->createTerm($this->vocabulary);
+    $term->name = $base . '/' . $this->randomName();
+    taxonomy_term_save($term);
+
+    // Try to autocomplete the term name, that contains a slash.
+    // We should only get a single term returned.
+    $input = substr($term->name, 0, 5);
+    $this->drupalGet('taxonomy/autocomplete/taxonomy_' . $this->vocabulary->machine_name . '/' . $input);
+    $this->assertRaw(drupal_json_encode(array($term->name => check_plain($term->name))), t('Autocomplete returns term %term_name after typing the first 4 letters, including a slash in the name.', array('%term_name' => $term->name)));
+  }
+
+  /**
    * Save, edit and delete a term using the user interface.
    */
   function testTermInterface() {