Objective To access the efficacy of the arterial based complexity (ABC) scoring system in predicting complexity of LPN.Methods A total of 70 patients underwent laparoscopic partial nephrectomy from January 2013 to November 2015 were enrolled in the retrospective analysis.Among those patients,53 (75.7％) were males and 17 (24.3％) were females.Their mean age was 52 years,ranged from 44 to 61 years.The average BMI was 28 kg/m2,ranged from 25 to 32 kg/m2.Before operation,the average creatinine was 70.5 μmol/L,ranged from 60.5 to 81.0 μmol/L.43 patients accepted the procedure via retro-peritoneal approach and 27 patients accepted the procedure via peritoneal approach.38 tumor located in the left kidney and 32 tumor located in the right kidney.By using ABC scoring system,four readers independently scored contrast-enhanced computed tomography images of 70 patients who underwent laparoscopic partial nephrectomy.Interobserver variability was assessed with kappa values and percentage of exact matches between each pairwise combination of readers.Logistics regression was used to evaluate the association between reference scores and ischemia time,estimated blood loss,operation time.Results The operative duration ranged from 100 to 180 min,mean 147 min.The mean ischemic time ranged from 15 to 37 min,mean 24 min.The average blood loss was 210 ml (ranging 50-380 ml).The mean hospitalization was 16 days (ranging 11-21 days).The urine leakage was noticed in 2 patients after the operation.The size of tumor ranged from 1.8 to 3.0 cm,mean 2.5 cm.The pathological classification included renal cell carcinoma in 65 cases,renal cell carcinoma with cystic changing in 2 cases,renal chromophobe cell carcinoma in 2 cases,right renal solitary fibroma in 1 case.Based on the ABC scorirng system,15 cases were in 1 degree,29 cases were in 2 degree,17 cases were in 3S degree and 9 cases were in 3H degree.Pairwise comparisons of readers' score assignments were significantly correlated;average kappa =0.492,across all reader pairs.The average proportion of exact matches was 65％,the average proportion that differ between a level or less than a level was 98.6％.Logistics regression between the complexity score system and surgical outcomes showed significant associations between reference category assignments and warm ischemia time and estimated blood loss (P ＜ 0.05),but showed no significant associations with operation time (P ＞ 0.05).Conclusions The ABC scoring system for LPN demonstrated good correlation with perioperative morbidity.This system is a novel anatomy-reproducible tool developed to help patients and doctors understand the complexity of renal masses and predict the outcomes of kidney surgery.