Purpose: We compared two surgical methods of augmentation cystoplasty (AC), before and after renal transplantation, and the outcomes of both methods with transplant patients with normal bladder function. Materials and Methods: 1520 kidney transplantation were performed at shahid Labbafinejad center between March 1988 and February 2002 of which 36 cases was accompanied with AC. In 20 patients (group A) AC was performed before transplantation. This group consisted of 14 males and 6 females with a mean age of 26.1 (13-39) at the time of transplantation. Sixteen patients consisting of 11 males and 5 females (mean age 27.3 , 12 - 44) underwent AC after transplantation. Eventually 40 transplant patients with normal bladder function were assigned in the control group including 18 males and 22 females with a mean age of 31.2 (11 - 55) (group C). Results: Normal graft function was achieved in 16, 13, and 33 patients of groups A, B, and C respectively over the mean follow - up of 70, 59 and 76 months (P<0.7). Mean serum creatinine during the follow - up was 1.48 ± 0.4, 1.7 ± 1 , and 1.4 ± 0.55 for groups A, B, and C respectively. 9 , 12, and 17 patients (26, 64, and 34 cases) with UTI requiring hospital admission were observed in the 3 groups respectively. The incident of UTI and the resultant hospitalization in group B was more than the one in group C (p<0.03), but it did not differ significantly from group A to group C. Conclusion: AC is a safe and effective method to improve the lower urinary system function and with the exception of increased risk of UTI following AC after transplantation (group B), there is no considerable difference in the complication rates between AC before and after renal transplantation. As a result, we can perform AC before or after kidney transplantation in patients with dysfunctional lower urinary tract system up to their specific conditions.