In this study we evaluated complications of ureteral anastomosis of kidney transplantation with two kinds of suture materials, Catgut chromic or fine prolene. In our study ureteral anastomosis was performed with 4-0 Catgut chromic sutures in 115 patients (group 1) and 5-0 fine prolene in 105 patients (group 2). All of the ureteral anastomosis was performed with modified lich technique. All the patients were followed for 18 months (2- 28). Urologic complications were assessed included stone formation in the site of the anastomosis, stricture, urinary leakage and urinary tracts infections (UTI). No stone formation was detected on the site of the anastomosis in both groups. 18.1% of patients in group 1 and 19.8% patients of group 2 experienced one episode of UTI (P>0.05). Three patients had urinary leakage and one patient had ureteral stricture in G1 and there was not any leakage or stricture in G2. Some collections were detected in 24.3 % of G1 and 18.1% of G2 (P>0.05). In our study urologic complications in G2 was not more than G1 and prolene can be used safely in ureteral anstomosis of renal transplantation.