Background/Aim. The treatment outcome of the median nerve compressive neuropathy in the carpal zone due to carpal tunnel syndrome (CTS) is represented by recovering the nerves sensibility, conductivity, condition and strength. Perineural application of betamethasone during the surgical decompression might result in faster recovery of compressed median nerve's conduction speed. Methods. In this study 40 patients with CTS were randomly divided in the two groups. In the first group (n = 20) we performed the surgical decompression of the median nerve by the open release of the carpal tunnel, and in the second group (n = 20) we applicated a perineural injection of 1 ml of betamethason immediately after the surgical decompression. We performed the electrodiagnostic (ED) examinations 7, 30 and 90 days after the surgery, and measured the conduction speed of the median nerve in the carpal tunnel zone and the sensitivity conduction speed of the median nerve. Results. Significant differences in examined ED respective variable values in different time intervals were obtained. At the final measurements, 90 days after the surgical procedure, both groups evidenced a full recovery of the conduction speed in the carpal tunnel with statistically significant better results in the second group of the patients (t = -2.116; p = 0.043). Conclusion. Intraoperative application of the corticosteroid injection during the surgical decompression results in faster regaining of conduction speed of the median nerve.