This study was conducted to examine the impact of CPB times on postoperative outcomes. We sought to determine the optimum cut-offs of CPB per graft time and cumulative CPB time and their predictive accuracy for mortality in conjunction with EuroSCORE II.The de-identified data of 1960 patients who had undergone isolated on-pump CABG from 2009 to 2014 were analyzed. The risk strata of cardiopulmonary bypass (CPB)/graft and cumulative CPB times, identified with a decision tree, were added into an augmented model for predicting short- and intermediate-term postoperative clinical events.Prolonged cumulative CPB time (>180 minutes) was significant in predicting mortality while adjusting for EuroSCORE II, postoperative complications, prolonged ICU stay and prolonged mechanical ventilation. Whereas prolonged CPB/graft time (>56 minutes) was marginally non-significant in terms of its direct effects, its indirect effect on mortality could be manifested through enhanced risks of complications, prolonged ICU stay (>48 hours) and prolonged mechanical ventilation (>24 hours).Prolonged CPB times could predict postoperative clinical events, in particular mortality. To minimize the occurrence of unfavorable adverse outcomes, it is recommended that the CPB/graft time and cumulative CPB time be kept below 56 minutes and 180 minutes respectively.