The purpose of this study is to evaluate the efficiency of local platelet-rich plasma (PRP) injection as an adjuvant treatment after carpal ligament release. We conducted a prospective randomized, tripleblinded, controlled trial. Fifty participants with mild to extreme carpal tunnel syndrome (CTS) were randomly assigned either to the PRP (n = 25) or the platelet-poor plasma (PPP, n = 25) group. After performing open surgical release of the carpal ligament, the inside of the carpal tunnel was irrigated with 3 mL of PRP or PPP according to each participant's group allocation. The primary outcome was hand grip strength (HGS). Secondary outcomes were the time taken off work after surgery (in days) and scores on the Wong-Baker Faces Scale, Boston Carpal Tunnel Questionnaire, and Southampton Wound Assessment Scale. We evaluated patients before treatment and at 6-weeks. As expected, the pain levels, symptom severity, and functional status improved in all the patients after surgery. However, intragroup analysis revealed that only the participants in the PRP group had regained their pre-operative HGS levels at 6-weeks follow-up. These findings indicate that PRP is an effective adjuvant treatment in patients with mild to severe CTS who require surgery. Carpal tunnel syndrome (CTS), which affects approximately 3% of the general adult population 1 , is the most commonly diagnosed upper limb peripheral entrapment neuropathy 2. CTS is characterized by compression of the median nerve (MN) at the wrist as it passes through the carpal tunnel 3 and typical symptoms include numbness, paresthesias, and pain in areas innervated by the MN. In more severe cases, weakness and atrophy of the thenar muscles (innervated by the MN) can occur which in turn, usually affects the work productivity and quality of life of the affected patient 4-6. Depending on the severity of the symptoms, treatments for CTS may be conservative (including the use of medications, a night splint, steroid injections, or physical therapy) or require surgical intervention. Surgical decompression of the carpal tunnel by transection of the transverse carpal ligament is the standard treatment for patients with muscle atrophy, or whose symptoms do not respond to conservative therapies 2,7. Carpal tunnel decompression is a well-established surgical treatment for CTS whose reported success rate and levels of patient satisfaction are high 8. Nonetheless, this technique is not exempt from potential complications including: sensitive scar areas, persistent symptoms, neurovascular injury, wound complications, bleeding, pillar pain (pain adjacent to the ligament release site), and reduced grip strength 9,10. Therefore, adjuvant surgical treatments are worth exploring. Platelet-rich plasma (PRP) is an autologous blood product comprising concentrated platelets and several growth factors (including transforming growth factor-β, platelet-derived growth factor, epidermal growth factor, vascular endothelial growth factor, insulin-like growth factor-1, fibroblast growth factor, hepatoc...