In five cases of suspected occult ganglion on the back of the wrist, an ultrasonographic examination was performed. This revealed a small hypoechogenic area on the dorsal aspect between the scaphoid and the lunate or just dorsal to the lunate. Exploration of this area in three cases confirmed the presence of an occult ganglion. In the other two cases, further aspiration revealed traces of mucinous jelly at the tip of the needle.