In this study, ulnar nerve entrapments at the wrist were investigated using nerve conduction studies in cases with established diagnosis of carpal tunnel syndrome (CTS). Cases with cervical radiculopathy and polyneuropathy as well as patients with ulnar nerve entrapment at elbow were excluded from the study. Fifty-three cases (46 females, seven males) whose ages ranged between 20 and 72 years (mean: 49.3 +/- 13.78) were evaluated. Among 53 cases, 12 (22.6%) bilateral and 41 (77.3%) unilateral CTS were detected. Totally 65 wrists evaluated and prolongation of median nerve wrist-3rd digit distal sensory latencies (DSL; n: 59; 90.7%) and wrist-abductor pollicis brevis distal motor latencies (n: 48; 73.8%) were seen. In six wrists, diagnoses were established with the detection of an increase in the differences between wrist-4th digit DSL of median and ulnar nerve. This test was used if other test results were in normal limits. Prolongation of ulnar nerve wrist-5th digit DSL were found in 12 wrists (18.4%) in cases with CTS. Among these 12 wrists mild (n: 2), moderate (n: 7) and severe (n: 3) CTS were detected. Ulnar nerve motor conduction studies provided normal results. In conclusion, we are in the opinion that for the detection of associated ulnar nerve wrist entrapments, ulnar nerve conduction studies paying special attention to DSL convey importance in established cases with CTS. (C) 2003, Editions scientifiques et medicales Elsevier SAS. All rights reserved.