Purpose: Wound healing is a series of restoration processes developing after dermal and soft tissue injury that is regulated by various factors. Among them, angiogenesis is an essential process that increases the tensile strength of wound and plays an important role in tissue regeneration. Sildenafil is a phosphodiesterase-5 (PDE-5) inhibitor that has been used commonly as a therapeutics for erectile dysfunction. Sildenafil induces vasodilation by blocking the degradation of nitric oxide (NO). High NO concentration has been reported to play a positive role in wound healing by accelerating angiogenesis, inflammatory reaction, and the proliferation of vascular endothelial cells. The present study assessed the effect of sildenafil on the wound healing process by examining wound contraction, tensile strength, and histological changes in response to the oral administration of sildenafil. Methods: Rats (n=120) were divided into the experiment group (n=60) and the control group (n=60), abdominal skin was incised up to the fascia. On postoperative day 10, 10 mg/kg sildenafil was administered to the experiment group. On postoperative day 4, 7, 14, 21, and 35, specimens were obtained from the incisional wound of 12 animals of each group. The wound tensile strength of each wound surface was determined, a histological evaluation was performed, and the change of the incisional wound area of the experiment and control groups was measured. Results: The tensile strength of wound was higher at 4, 7, and 14 postoperative day in the sildenafil treated group than control. In histologic findings, acute and chronic inflammatory reactions were not significantly different. The formation of granulation tissues, collagen deposition, and reepithelialization did not show significant differences. Nonetheless, concerning the collagen deposition score, except on day 35, the averages were higher in the experiment group. The angiogenesis scores on postoperative day 4, 7, 14, 21, and 35 were higher in the experiment group. Postoperatively, wound contraction was significantly greater in the experiment group, although they were not significant from postoperative day 14 onward. Conclusion: In the rat abdominal wound model, orally administered sildenafil accelerates wound healing by facilitating angiogenesis, and is beneficial during the process of wound contraction.