Background: Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy. Platelet-rich plasma (PRP) therapy is a simple, low cost and minimally invasive method that contains a natural concentrate of autologous growth factors. It was found that PRP has therapeutic effects on many neuropathies which synergizes nerve regeneration, but its effects on carpal tunnel syndrome are unclear. The aim of wok is to evaluate the effectiveness of PRP injections in carpal tunnel syndrome clinically and electrophysiologically. Subjects & Methods: We performed this clinical trial study on 18 patients with idiopathic mild to moderate carpal tunnel syndrome who received single injection of PRP into the carpal tunnel. Nerve conduction studies (NCS) were carried out, Visual Analogue Scale (VAS) and the Boston Carpal Tunnel Questionnaire (BCTQ) were administered to patients immediately before treatment, one and three months after treatment. Results: PRP injection showed significant improvement of patients as regard VAS, symptom severity scale (SSS) and functional status scale (FSS) of BCTQ after one and three months of injection. Also, we found that PRP injection showed significant difference in distal motor and sensory latency, amplitude of compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) and sensory conduction velocity of the median nerve after one and three months of injection Conclusion: local injection of the PRP proved to be available safe choice therapy for carpal tunnel syndrome. Key words: carpal tunnel syndrome; platelet-rich plasma; nerve conduction studies