Objective: To compare the success and complication rates and advantages and disadvantages of retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PNL) methods for the upper calyceal renal stones between 10 and 20mm. Materials and Methods: The files of 124 patients who had upper calyceal renal stones in diameter 10-20mm were analyzed retrospectively. Sixty-one patients were randomized as Group 1 and 63 as Group 2. The parameters as success and complication rates, fluoroscopy and operation times, preoperative and postoperative hemogram (Hb) levels, and need of blood transfusion were saved and then groups compared. Complication rates and need of second procedure numbers between groups were evaluated according to modified Clavien classification. Results: Demographic features and success and complication rates between groups were similar. Hospitalization time was 1.00.1 day for Group 1 and 2.3 +/- 1.4 days for Group 2. When preoperative and postoperative Hb difference was evaluated, 0.1 +/- 0.3mg/dL decrease was noticed for Group 1 and 1.6 +/- 0.8mg/dL decrease for Group 2. Mean operation time for Group 1 was 53.6 +/- 15.1 minutes and mean fluoroscopy time was 20.1 +/- 8.9 seconds for Group 1; for Group 2, these values were 67.8 +/- 16.2 minutes and 53 +/- 15.0 seconds, respectively. As a result, mean operation time and fluoroscopy time, hospitalization time, and Hb decrease levels were found less and as statistically significant for Group 1. Conclusion: RIRS and PNL methods both have the same success and complication rates for upper calyceal renal stones between 10 and 20mm. However, we think that RIRS method should be preferred for suitable patients because it is a more noninvasive method and has advantages of some operation parameters over PNL.