Introduction: To evaluate the clinical and electrophysiologic features of ulnar nerve entrapment neuropathies proximal tothe medial epicondyle, especially those caused by working while leaning on the elbow.Methods: In this study, the data of 234 patients who were admitted to the EMG Laboratory of the neurology clinic withcomplaints of numbness in the fourth and fifth fingers, ulnar weakness, and in addition, ulnar entrapment neuropathy wasdetected in their electrophysiological examinations. In 175 (74.8%) of these patients, ulnar entrapment neuropathy wasdetected proximal to the medial epicondyle. The study was continued with these 175 patients. The findings obtained fromthe electrophysiological and clinical examinations of the patients were analyzed.Results: Entrapment was in the left side in 96.57% of the patients, whereas it was right-sided in 3.43% (p<0.001). Ulnar nervemotor responses were investigated as above elbow, under elbow, and wrist. Above elbow latency, motor response duration,amplitude and field results were measured as 8.69±1.24 ms, 12.56±2.73 ms, 3.64±2.24 mV and 11.62±7.37 mV*ms, respectively.When compared the results of above elbow with wrist and under elbow, amplitude and field were decreased and latency wereprolonged (p<0.001, p<0.001, p<0.001, respectively). There wasn’t statistical difference between the groups in the ulnar nervemotor response duration (p<0.001). Above elbow to under elbow nerve conduction velocity was 33.98±8.35 m/s, and underelbow to wrist nerve conduction velocity was measured as 61.99±4.23 m/s. Above elbow to under elbow conduction velocitywas found to be slower (p<0.001). Demyelinating lesions were detected in 83.4% and axonal lesions in 16.6%.Discussion and Conclusion: It was shown that ulnar nerve entrapment proximal to medial epicondyle was the most com-mon type among all ulnar nerve entrapments. This acute entrapment was associated with hand dominance and was mostcommonly seen in demyelinating character.