Index: sites/all/modules/mailchimp/mailchimp.module
===================================================================
--- sites/all/modules/mailchimp/mailchimp.module	(revision 1800)
+++ sites/all/modules/mailchimp/mailchimp.module	(working copy)
@@ -654,6 +654,7 @@
  */
 function _mailchimp_interest_groups_element($q, $list_id, $groupings = array(), $is_subscribed = FALSE) {
   $element = array();
+  $all_hidden = TRUE;
   if ($groups = $q->listInterestGroupings($list_id)){
     $element['interest_groups_' . $list_id] = array(
       '#type' => 'fieldset',
@@ -668,6 +669,7 @@
     foreach($groups as $group) {
       // ignore hidden groups
       if ($group['form_field'] != 'hidden') {
+        $all_hidden = FALSE; // Make sure at least one grouping is displayed
         $default = array();
         if (!empty($groupings)) {
           foreach($groupings as $grouping) {
@@ -704,8 +706,7 @@
       }
     }
   }
-
-  return $element;
+  return ($all_hidden) ? array() : $element;
 }
 
 /**