Carpal tunnel syndrome (CTS) is a common entrapment neuropathy worldwide.This study aimed to investigate the temporal changes in electrophysiological parameters in untreated patients with CTS. Patients were recruited among those with the symptoms of CTS who were referred to the electrophysiology laboratory of Niğde Ömer Halisdemir University Bor Physical Therapy and Rehabilitation Hospital in Niğde, Turkey. Forty-nine patients (78 hands) who had not received any sort of treatment for CTS and had prior electrophysiological examination postive for CTS were included.Laboratory records were reviewed retrospectively. Recent electrophysiological parameters of the patients were compared to their prior examinationsusing Wilcoxon signed-rank test and sign test was used to compare the change in the electrophysiological severity of the study hands between two examinations. One-way analysis of variance(ANOVA) was used to compare individual parameters of the median NCS amongelectrophysiological change groups (improved, deteriorated, and same). The mean age was 50 ± 11 years, and 43 (88%) patients were female. The mean duration of time between the two electrophysiological examinations was 37 ± 20 months. Median sensory peak latency and median motor distal latency increased significantly in the second evaluation (p=0.005 and p=0.004, respectively). Median sensory conduction velocity decreased in the second examination (p=0.002). However, CTS severity determined electrophysiologically did not differ significantly in the two examinations (p=0.286). Although there was a deterioration in electrophysiological parameters during a mean follow-up period of 37 months, the electrophysiological severity of the patients did not worsen.