Carpal tunnel syndrome(CTS) is the most common neuromuscular cause of upper extremity disability. We aimed to investigate the effectiveness of peloid therapy in patients with CTS. This randomized, controlled, single-blind study enrolled 70 patients between the ages of 30 to 65 who had a diagnosis of either mild, mild-to-moderate, or moderate CTS. The patients were randomized into two groups using random number table. In the first group, (Group 1)(n = 35), patients were given splint (every night for 6 weeks) + peloid treatment(five consecutive days a week for 2 weeks) and in the second group, (Group 2)(n = 28), patients received splint treatment(every night for 6 weeks) alone. The patients were assessed by using visual analog scale(VAS) for pain, electroneuromyography(ENMG), the Boston Carpal Tunnel Syndrome Questionnaire(BCTSQ), hand grip strength(HGS), finger grip strength(FGS), and Short Form-12(SF-12). The data were obtained before treatment(W0), immediately after treatment(W2), and one month after treatment(W6). Both in Group 1 and 2, there was a statistically significant improvement in all the evaluation parameters at W2 and W6 when compared to W0(p < 0.05). Comparison of the groups with each other revealed significantly better results for VAS, BCTSQ, mSNCV, SF-12 in Group 1 than in Group 2 at W2(p < 0.05). There was also a statistically significant difference in favor of Group 1 for VAS, BCTSQ, FGS and MCS at W6 when compared to W0 (p < 0.05). The results of our study demonstrated that in patients with CTS; peloid + splint treatment was more effective than splint treatment alone in pain, functionality and life quality both at after treatment(W2) and one month after treatment (W6). We may suggest peloid as a supplementary therapeutic agent in CTS.