Background: Peripheral nerve injuries are an important clinical issue. Biological treatments are thought to boost nerve regeneration and improve functional outcomes after damage despite advancements in microsurgical procedures to increase nerve healing. Objective: The present study aimed to evaluate the effect of autologous fat grafting on nerve regeneration in rats. Materials and methods: This study included 24 Sprague-Dawley adult male rats with an average weight of 250-350 grams that were anesthetized properly and had a sciatic nerve transected and repaired primarily using 9/0 polypropylene sutures under a surgical microscope then divided into two groups: (1) Therapeutic group in which3 mL processed fat placed around epineurial repair siteand(2) Control group in which primary epineurial repair only performed. Results: Eighteen rats survived the experiment till the end of the 12^th week. They started moving around an hour postoperatively and started drinking and feeding approximately 4 hours later. The skin sutures were removed 7 days postoperatively showing a satisfactory wound healing. The rats showed improved mobility and motor power in the surgical limb towards the end of the 8th week. Three rats died postoperatively due to anesthesia complications, two more died in the second week due to infection/ulceration of the surgical limb and the sixth died in the 5th week post-operative due to peer violence from the other rats totaling in 6 casualties. Conclusion: There was an increase in the number of regenerated nerve fibers in the fat grafted group 1 on the proximal and distal end in comparison with the control group 2.