Background: Percutaneous nephrolithotomy (PNL) is the first line treatment for kidney stones with a diameter > 2 cm. The available scores for measuring success in this procedure only consider the free stone status, without considering the complications. Objective: To present a new prognostic stratification system to predict treatment failure in PNL. Material and methods: Historic cohort in which prognostic factors and failure as residual stone with or without complication were identified. A bivariate analysis was performed using the numeric variables and with the use of conjunctive consolidation a prognostic stratification system was developed. Results: A total of 595 cases were included, out of which 73% concluded with free stone status and 12% developed major complications. 66% fulfilled the proposed success definition. In the first conjunct consolidation, a positive urine culture and a complex stone were identified as risk factors; after making one more conjunction with another stratum, the severe Charlson Comorbidity Index (CCI) was also identified as a risk factor. Finally, an operating time ≥ 120 minutes was added as an intraoperative factor that increases risk. Conclusions: The variables positive urine culture, severe CCI, complex stone and prolonged operating time are associated with major complications and residual stone. The proposed score is a simple and predictive tool that can be used in daily practice, given that it includes 3 pre-operative variables. The treatment success or failure rate of the score can be applied in the selection of patients ongoing PNL