AbstractAt the elbow the ulnar nerve may be compressed either in the retrocondylar groove or at the cubital tunnel. Optimal surgical therapy should be directed at the specific site of involvement. Intraoperative electroneurography performed in conjunction with 19 ulnar nerve explorations helped localize the precise site of compression. Of the primary procedures, abnormality was at the retrocondylar groove in 9, cubital tunnel in 4, both locations in 3, and at an unusual distal point in 1; 12 anterior subcutaneous transpositions, 4 cubital tunnel releases, and 1 distal decompression resulted. Intraoperative studies helped identify residual compression in two patients undergoing reexploration. Although routine electrodiagnosis may localize an ulnar neuropathy to the elbow, reliably separating retrocondylar from cubital tunnel compression is more difficult. Preoperatively, percutaneous serial short increment studies were more accurate than simple “inching” in predicting the site of compress