Objectives: At present, there is no report on the application of Guy's stone (GS) score in minimally invasive percutaneous nephrolithotomy (MPCNL). We therefore investigate the clinical effect of MPCNL by using a patented irrigation and clearance system according to the GS. Methods: A total of 222 consecutive patients were divided into 2 groups that were treated with MPCNL using the patented system or standard PCNL using Electro Medical System (EMS) ultrasound/ballistic trajectory lithotripsy and clearance system, respectively (124 patients in patented system group, 98 patients in EMS system group). The stone complexity and severity of complications were stratified by GS and Modified Clavien grading system in this study, respectively. The success and complication rates between MPCNL and PCNL were compared. Results: The patented system group had a significantly higher success rate (GS3: 95 vs. 43% and GS4: 67 vs. 31%) and a significantly less complications rate (GS3: 12 vs. 27% and GS4: 21 vs. 46%) in GS3 and GS4 compared with the EMS system group. Also, the patented system had significant lower complication rates in Clavien grades II-IV than that of the EMS system. Conclusion: The MPCNL using the patented irrigation and clearance system was more efficient in dealing with renal stones of high complexity (GS3-4). (C) 2016 S. Karger AG, Basel