diff --git a/expire.admin.inc b/expire.admin.inc
index 957fd012e822be201d3e5460c95ec4e80568145d..ec84f50e3d6c95e63551e675003891947b00051d 100644
--- a/expire.admin.inc
+++ b/expire.admin.inc
@@ -57,6 +57,21 @@ function expire_admin_settings_form() {
     '#markup' => $modules ? theme('item_list', array('items' => $modules)) : t('There are no implementations.'),
   );
 
+  $form['tabs']['status']['debug'] = array(
+    '#type' => 'fieldset',
+    '#title' => t('Debug'),
+  );
+
+  $form['tabs']['status']['debug']['expire_debug'] = array(
+    '#type' => 'radios',
+    '#title' => t('Debug level'),
+    '#options' => array(
+      EXPIRE_DEBUG_DISABLED => t('Disabled'),
+      EXPIRE_DEBUG_WATCHDOG => t('Watchdog'),
+      EXPIRE_DEBUG_FULL => t('Watchdog + site message'),
+    ),
+    '#default_value' => variable_get('expire_debug', EXPIRE_DEBUG_DISABLED),
+  );
 
   // NODE SETTINGS.
   $form['tabs']['node'] = array(
diff --git a/expire.module b/expire.module
index ef5d20911503c876a0bc8c22a6e9955e87f34697..9dc8db391a6e0d1fff1117bbe24e1eb93d33dd6a 100644
--- a/expire.module
+++ b/expire.module
@@ -36,6 +36,11 @@ define('EXPIRE_USER_CANCEL', 4);
 define('EXPIRE_VOTINGAPI_INSERT', 1);
 define('EXPIRE_VOTINGAPI_DELETE', 2);
 
+// Debug levels.
+define('EXPIRE_DEBUG_DISABLED', 0);
+define('EXPIRE_DEBUG_WATCHDOG', 1);
+define('EXPIRE_DEBUG_FULL', 2);
+
 // Default values for cache expirations.
 define('EXPIRE_NODE_FRONT_PAGE'             , FALSE);
 define('EXPIRE_NODE_NODE_PAGE'              , TRUE);
diff --git a/includes/expire.api.inc b/includes/expire.api.inc
index 73fe5807c8305070d457ab67d335d6d3784dda70..e009b85d014612447259b6244c797869f4027d4b 100644
--- a/includes/expire.api.inc
+++ b/includes/expire.api.inc
@@ -36,6 +36,9 @@ class ExpireAPI {
       list($absolute_urls, $wildcards) = self::convertToAbsoluteUrls($urls);
     }
 
+    // Write some debug information.
+    self::debugLog($absolute_urls, $wildcards, $object_type);
+
     $status = variable_get('expire_status', EXPIRE_STATUS_DISABLED);
     if ($status == EXPIRE_STATUS_ENABLED_INTERNAL) {
       self::executeInternalExpiration($absolute_urls, $wildcards);
@@ -227,4 +230,37 @@ class ExpireAPI {
     return array($absolute_urls, $wildcards);
   }
 
+  /**
+   * Log debug information.
+   *
+   * @param $absolute_urls
+   * @param $wildcards
+   * @param $object_type
+   */
+  protected static function debugLog($absolute_urls, $wildcards, $object_type) {
+
+    $debug = variable_get('expire_debug', EXPIRE_DEBUG_DISABLED);
+    if (empty($debug)) {
+      return;
+    }
+
+    $output_urls = array();
+    foreach ($absolute_urls as $internal_path => $url) {
+      $wildcard = !empty($wildcards[$internal_path]) ? 'true' : 'false';
+      $output_urls[] = t('URL: @url', array('@url' => check_url($url)));
+      $output_urls[] = t('Wildcard: @wildcard', array('@wildcard' => $wildcard));
+      $output_urls[] = t('Expired object: @type', array('@type' => $object_type ? $object_type : '(none)'));
+      $output_urls[] = '--------';
+    }
+
+    // Log debug message in watchdog.
+    $message = t('Expiration was executed for the next URLs: !urls', array('!urls' => theme('item_list', array('items' => $output_urls))));
+    watchdog('expire', $message, array(), WATCHDOG_DEBUG);
+
+    // For development might be useful to print info on screen.
+    if ($debug == EXPIRE_DEBUG_FULL) {
+      drupal_set_message($message);
+    }
+  }
+
 }