Background and purpose: Carpal tunnel syndrome (CTS) is one of the most common neuropathies caused by entrapment of the median nerve in the wrist. The purpose of this study was to evaluate the electrodiagnostic changes before and after carpal tunnel release (CTR). Materials and methods: The present descriptive study was conducted in 24 patients (38 hands) with CTS in order to evaluate the electrodiagnostic changes before and 12 months after CTR and to investigate the relationship between electrodiagnostic changes and Boston score, DASH score, and Grip and Pinch strength. Data were analyzed using SPSS V20. Results: Electrodiagnostic study showed that the mean distal motor latency (DML) significantly decreased from 6. 7 ±, 2. 12 ms to 4. 70 ±, 0. 61 ms (P=0. 0001) and the mean distal sensory latency (DSL) significantly improved (from 4. 98 ±, 1. 06 ms to 4. 54 ±, 0. 75 ms, P=0. 012). Findings showed no significant differences in mean DML and DSL between right and left hands (P=0. 378, P=0. 233). There was a significant positive correlation between age and DML and DSL after CTR (r=0. 475, P=0. 001, and r=0. 341, P=0. 024, respectively). No significant correlation was observed between postoperative electrodiagnostic findings and Boston score, DASH score, and Grip score ({sss: P=0. 931, fss: P=0. 629}, P=0. 169, P=0. 1000, respectively). Conclusion: Postoperative electrodiagnostic findings significantly improved, but there was no clear association between EMG NCV and the severity of postoperative clinical symptoms. Therefore, in order to evaluate the outcome of CTR, combination of clinical symptoms with electrodiagnostic findings is considered valuable.