Introduction: Definitive consensus on grading of complications of shock wave lithotripsy (SWL) does not exist. The objective of this study was to grade complications of SWL in relation to different stone and shock wave parameters, according to the modified Clavien system. Materials and Methods: Complications observed in 2,648 patients who underwent SWL between January 2003 and May 2014 were evaluated statistically and stratified into 5 grades by the modified Clavien system focusing on stone and shock wave parameters. Results: Statistically significant association (p ≤ 0.05) was found between SWL outcome, Clavien grade of complications and stone and shock wave parameters. According to the modified Clavien system, grades I, II, IIIa, IIIb, IV and V complications were observed in 1,811 (68.39%), 619 (23.37%), 183 (6.91%), 34 (1.28%), nil (0.00%) and 1 (0.03%) patients, respectively. The overall success rate at 3 months was 87.72%. Conclusions: The modified Clavien system provides a standardized grading of SWL complications and can be used to standardize procedural errors and maintain quality, thereby preventing associated complications and improving the overall management and hence outcome of SWL.