Aim: To examine the effect of ureterorenoscopic stone removal timing on kidney function in unilateral ureteral stones. Methods: The 137 patients sampled were divided into two groups: 98 patients who underwent surgery ≤ 14 days after the stone diagnosis (Early Surgery Group) and 39 patients who were operated> 14 days after the stone diagnosis (Late Surgery Group). Preoperative serum creatinine, blood urea nitrogen (BUN), and GFR were recorded for the patients in both groups. In the postoperative first mouth, serum creatinine, BUN, and GFR were again recorded and compared with the preoperative values. Result: The mean preoperative serum creatinine, GFR, and BUN levels for Early Surgery Group were 1.25 ± 0.65µmol/L, 80.04 ± 33.6ml/min/1.73m2, 50 ± 16.6mmol/L, respectively. While a decrease was observed in serum creatinine (0.82 ± 0.22µmol/L, p < 0.001) and BUN (14.08 ± 7.25mmol/L, p < 0.001) levels one month after surgery, the GFR increased (105.33 ± 21.6ml/min/1.73m2, p < 0.001). In Late Surgery Group, postoperative serum creatinine levels increased minimally (0.94 ± 0.33 vs. 0.95 ± 0.30µmol/L, p = 0.102), and GFR decreased (95.15 ± 27.3 vs. 93.77 ± 24.3ml/min/1.73m2, p = 0.338). Although there was an increase in BUN (17.38 ± 9 vs. 17.92 ± 8.8mmol/L, p = 0.283), the statistical difference was not significant. Conclusion: We believe that surgical treatment should be planned within two weeks at the latest, as prolonged obstruction may result in kidney damage