ABSTRACT Purpose: To investigate the effect of robot assisted laparoscopic radical prostatectomy (RALP) and open retropubic radical prostatectomy (RRP) on early renal function in this study. Materials and Methods: Preoperative and postoperative urea, creatinine, Hb, eGFR values of patients who had undergone RALP and RRP with prostate cancer (PCa) diagnosis were recorded in our clinic. The percentages of change in these values are calculated. Preoperative and postoperative urea, creatinine, Hb and eGFR changes were compared with each other. Student-t test was used for intergroup comparison, and paired sample t test was used to compare changes between preoperative and postoperative values of the same group. Results: There were 160 and 93 patients in the RALP and RRP group, respectively. In the RALP group, postoperative urea and creatinine increased significantly compared to preoperative baseline values while eGFR was decreased (p = 0.0001, p = 0.001, p = 0.0001, respectively). Except for Hb in the RRP group, the changes in these values were statistically insignificant (p = 0.50, p = 0.75, p = 0.30, respectively). Conclusions: We should be more careful when we perform RALP in patients at risk of impaired renal function despite being a minimally invasive surgical method with superior visual characteristics.