Compression neuropathy of ulnar nerve is the most frequent entrapment neuropathy after carpal tunnel syndrome. Because of its anatomic localization, it is mostly trapped in elbow and secondly the wrist. Even though it is mostly compressed in cubital tunnel and retroepicondylar groove in the elbow; other possible regions where trapping may occur are arcade of Struthers, medial intermuscular septum and flexor-pronator aponeurosis. Due to the level of trapping in wrist, signs may be pure sensorial, pure motor or mixed. Guyon canal is one of the most common trapping region for ulnar nerve in wrist. The most important cause of trapping in Guyon canal is room occupying lesions. Diagnosis is made according to symptoms, physical examination findings or electrodiagnostic and radiologic studies. There are both conservative and surgical treatment options. Surgery is performed in patients if they do not respond to conservative treatment. All surgical treatment options give satisfying functional results for cubital tunnel syndrome. The results of trapping in wrist usually depends on its etiology. In this review; first the pathophysiological, clinical and electrophysiological diagnosis of ulnar nerve trapping, and then its surgical treatment options and results will be discussed.