Objective: Microsurgical tissue transfers are widely used for the reconstruction of the defects resulting from the excision of the malignancies and adjuvant therapies are also commonly employed in order to improve the survival. After surgery, further need for chemotherapy and radiotherapy is not uncommon. However, these treatment modalities may have adverse effects on each other. Effects of chemotherapeutic agents on microvascular anastomosis should be known well so that treatment plan can be done. Mitomycin C is one of the most toxic chemotherapeutic agents. In this experimental study we have investigated the effects of mitomycin C on the microvascular anastomosis. Material and Methods: Twenty Sprague-Dawley rats were used. 10 mg/m2 Mitomycin C was administered intraperitoneally to 10 animals in study group. The other 10 animals were used as the control group. One week later microvascular anastomoses were carried out on femoral arteries of all of the animals. Results: After two weeks of waiting period, animals were reoperated and patency of the anastomoses were checked, also a histologic study was carried out. Macroscopically pulsatile blood flow was observed in all but two animals in study group and one animal in control group. Histologically, no additional reaction against mitomiycin C in muscular and adventitial layers of the vessel walls was observed. We found out that there was no significant difference between the animals in control group and study group in terms of patency of the anastomoses and histological findings. Conclusion: Since Mitomycin C is one of the most toxic chemotherapeutic agents it is important to know that it does not affect the microvascular anastomoses adversely. © 2010 by Türkiye Klinikleri.