Platelet-rich plasma (PRP) treatment has a potential to become a part of nonsurgical approach in carpal tunnel syndrome (CTS) as a regenerative method. PRP therapies aim to enhance the self-healing ability of human body, by exposing the injured tissue to a high concentration of autologous growth factors. Nerve tissues also seem to benefit from the regenerative effects of PRP concentrates. The aim of this study is to investigate the possible beneficial effects of PRP injection in CTS. A total of 40 hands of 30 patients were included (20 hands per group) with mild to moderate idiopathic CTS. Patients with mild to moderate CTS were placed into either control or PRP groups. Activity modification and night-only wrist splints were suggested in both groups. Additionally, in PRP group, a single perineural PRP injection into the carpal tunnel was applied under ultrasound guidance. Sensibility tests, Boston carpal tunnel questionnaire (BCTQ), and electrophysiological and ultrasonographical findings were measured initially and after 4 weeks. Groups were similar regarding demographics. BCTQ scores and ultrasonographical values were improved in both groups. Delta analyses revealed that the difference of BCTQ scores improved better in PRP group. Electrophysiological values improved in PRP group. Our study demonstrated that a single, perineural PRP injection into carpal tunnel provided further improvements in CTS.