INTRODUCTION AND OBJECTIVES: The S.T.O.N.E. nephrolithometry was previously developed to quantitate stone complexity. We assessed the ability of nephrolithometry score to predict stone-free status in a multicenter database of patients undergoing PCNL. METHODS: We performed a multicenter retrospective study of patients undergoing PCNL. Preoperative CT images were reviewed and S.T.O.N.E. score was assigned to each patient. The association of S.T.O.N.E. score with patient demographics, stone characteristics, and surgical outcomes was analyzed. RESULTS: In total, 706 met inclusion criteria and were included in the analysis. Mean overall nephrolithometry score was 8.2 (SD = 2.2). Overall single procedure stone-free rate was 69%. In logistic regression analysis, S.T.O.N.E. score was significantly associated with postoperative stone-free status (P < 0.001). Stonefree patients had statistically significant lower S.T.O.N.E. scores than patients with residual stones (7.7 vs. 9.1, respectively; P < 0.001). On average, for each increase in one unit of S.T.O.N.E score, odds of being stone-free decreased by 32%. In risk stratification, low-risk patients with 5–7 scores had 22.8% of residual stones, compared to medium-risk (8–10) and high-risk patients (11–13) who had 50.8% and 66.7% of residual stones, respectively (p = 0.001). On average, compared to scores 5–7, scores 8– 10 and 11–13 have a decrease in the odds of being stone free by 71% and 85%, respectively. CONCLUSIONS: In a multicenter study including data from multiple surgeons, S.T.O.N.E. nephrolithometry accurately predicted stone-free rate following PCNL. The easy-to-use scoring system obtained from CT imaging may be utilized in preoperative patient counseling, surgical planning, quality assessment, and as a standardized measure to evaluate outcomes across different series. SOURCE OF FUNDING: None