The ulnar nerve has to bear a large amount of compression, especially in the cubital tunnel, which can be deducted from the topographic relation of this nerve to the elbow. Apart from tightness of the tunnel, intraarticular changes can also cause compression of the nerve. A further narrow tunnel in the course of the ulnar nerve is the "loge de GUYON", situated in the hypothenar region. A careful neurological examination of sensory and motor signs as well as an accurate electromyographical examination differentiate compression syndromes from other neuropathies. Two unusual cases of a functional cubital tunnel syndrome are demonstrated: their cause was primarily a chondromatosis of the elbow joint in one case a functional vasal compression in the other case.