To compare the amount of the kidney displacement in the complete supine percutaneous nephrolithotripsy (PCNL) to the prone PCNL during getting renal access. Thirty-three patients were randomly divided into two groups. The patients in group A were placed in the complete supine position and the patients in group B in the prone position. Amounts of the kidney displacement in three states and other data were analyzed. The mean amount of the kidney displacement in the complete supine PCNL was 10.1 ± 7.9 mm in stage 1, 10.7 ± 8.28 mm in stage 2 and 12.2 ± 10.4 mm in stage 3. The mean amount of the kidney displacement in prone PCNL was 16.6 ± 5.8 mm in stage 1, 16.2 ± 6.3 mm in stage 2 and 17.6 ± 6.7 mm in stage 3. In stages 1 and 2, a significant difference between the two groups derived from the mean amount of the kidney displacement, but the difference was not statistically significant in stage 3. Adjusted for age, gender, BMI, stone burden and position of PCNL, prone position was a predictor caused significantly more displacement in all three stages. Among other predictors, only BMI had a significant effect on the amount of the kidney displacement (in stages 2 and 3). Performing PCNL in the complete supine position is safe and effective and leads to less kidney displacement during getting renal access and therefore, it may be considered in most patients requiring PCNL.