Introduction & Objective: Transurethral resection of prostate (TURP) is the most popular procedure for benign prostate hyperplasia (BPH). Several different irrigation solutions have been proposed for this procedure, but some controversies exists in their selection. This study aimed to compare sterile water with 1.5% glycine as irrigation solution for transurethral resection of prostate. Materials & Methods: In this clinical trial all patients who were candidates for TURP were randomly assigned into two groups based on irrigation solution of procedure, sterile water group and 1.5% glycine group. Pre- and postoperative clinical and paracinical data was gathered and analysised by SPSS 11.5 for Windows software package, using t-test and chi-square tests. P-values less than 0.05 considered statistically significant. Results: The number of 80 patients was assigned randomly to receive strile water and glycin (each group had 40 patients). Patients age, weight of resected prostate and total volume of irrigation solution was not significantly different between two groups. Post-operative serum sodium, potassium, urea and creatinin levels decreased significantly in both groups; but there were no difference between groups in respect to these parameters. The Post-operative decline of hematocrit and hemoglobin in glycine group was significantly greater than water group (-4.22±4.24% v.s -1.3±4.25% and -1.47±1.96 mg/dl v.s -0.46±1.6 mg/dl, respectively). Twenty four patients among all studied cases (30%), developed signs and symptoms including nausea, vomiting, headache, dyspnea, tachypnea and blood pressure rise. There was no significant difference in the rate of development of these problems between two groups. TUR syndrome requiring medical intervention, developed in only 2 patients (2.5%) which one of them was in glycine and the other was in water group. Both of these patients recovered completely following conventional medical measures. Conclusions: In this study there was no difference in alterations of sodium, potassium, urea, creatinine and development of TUR syndrome between two groups and post-operative decline of hematocrit and hemoglobin levels in water group was significantly milder. Thus, utilization of water as a cheap and available irrigation solution can be suggested in groups of patients.