ABSTRACT Background: Tendon injury represents a common cause of morbidity worldwide and is one of the commonest causes of disability especially among the worker group. Many theoretical and clinical studies support the efficacy of platelet rich plasma (PRP) in augmenting healing in different human body aspects. Objective: Assessing the efficacy of PRP in primary flexor tendon repair. Patients and methods: The study was prospective controlled clinical study included 40 patients visiting Al-Azhar University Hospital's emergency departments 20 of them treated with the conventional method the other 20 patients treated in the conventional method + PRP injection the cases treated and followed over period of December 2019 till October 2020. Results: When comparing patient's characteristic in the two groups, there was no statistical difference between study groups regarding age, sex, affected side, zone of injury and tendon affected. However, there was a statistical difference between studied groups as regards 2nd and 3rd week pain scale follow up. There was no statistical difference between studied groups regarding 1st, 2nd & 3rd week TAROM%, and between studied groups regarding U/S assessment. There was a statistical difference between studied group regarding time of resuming activities with median of 4 SD 4-6 in group 1 (PRP Group) (p-value < 0.05), and median of 6 weeks SD 6-8 in group 2 (Non-PRP). Conclusion: PRP injection is a simple, cost-effective procedure that shows significant promise in improving postoperative healing and pain.