Abstract Background To investigate the effect of platelet-rich plasma (PRP) on TGF-β1 expression during tendon healing. Methods We used 48 skeletally mature New Zealand White rabbits. 24 rabbits received the PRP, and 24 rabbits served as an untreated control group. Equal numbers of animals were sacrificed at 1st, 2nd, 3rd, and 4th week. The surgical procedure involved a transverse incision to transect the Achilles tendon. A volume of 1 ml of PRP was then injected into the tendon mass in the PRP group. Histological and immunohistochemical evaluations with an anti-TGF-β primary antibody were performed. Results The pattern of expression of TGF-β1 in the PRP group was characterized by a significant upregulation during the first 2 weeks and subsequently significant downregulation in the 3rd and 4th week in comparison with the controls. Conclusions Our results suggest that PRP may affect the tendon healing process by altering the expression of TGF-β1.