Index: tests/Zend/Db/Select/TestCommon.php
===================================================================
--- tests/Zend/Db/Select/TestCommon.php (revision 24461)
+++ tests/Zend/Db/Select/TestCommon.php (working copy)
@@ -1609,6 +1609,18 @@
         $this->assertEquals(1, $result[0]['id']);
     }
 
+    public function testSelectUnionBind()
+    {
+        $select1 = new Zend_Db_Select($this->_db);
+        $select1->from('foo')->joinLeft('bar', 'bar.id = :BIND1')->bind(array('BIND1' => '1'));
+        $select2 = new Zend_Db_Select($this->_db);
+        $select2->from('foo')->joinLeft('bar', 'bar.id = :BIND2')->bind(array('BIND2' => '2'));
+
+        $select3 = new Zend_Db_Select($this->_db);
+        $select3->union(array($select1, $select2));
+        $this->assertEquals(array('BIND1' => 1, 'BIND2' => 2), $select3->getBind());
+    }
+
     /**
      * @group ZF-4772
      * @expectedException Zend_Db_Select_Exception
Index: library/Zend/Db/Select.php
===================================================================
--- library/Zend/Db/Select.php  (revision 24461)
+++ library/Zend/Db/Select.php  (working copy)
@@ -292,6 +292,9 @@
         }
 
         foreach ($select as $target) {
+            if ($target instanceof Zend_Db_Select) {
+                $this->_bind = array_merge($this->_bind, $target->_bind);
+            }
             $this->_parts[self::UNION][] = array($target, $type);
         }