It is reported that the mortality rate for combined coronary bypass grafting and mitral valve replacement is greater than for either isolated operation. To evaluate the effects of various predicting factors we analyzed the results of 67 consecutive patients undergoing combined mvr and CABG. The mean age was 61.3 +/- 7 years. There were 55 males and 12 females and the mean follow-up was 59.4 +/- 7 months. The hospital mortality rate was 13.4% (9/67). Preoperative NYHA functional class (p<0.05), left-ventricular motion score (increased scores indicating impaired function, (p<0.05), and aortic cross-clamp time (p<0.05) were associated with hospital mortality. There was no significant relationship of age (>60), cause of mitral valve disease, severity of mitral regurgitation, number of grafts, or previous myocardial infarction with hospital mortality. There were 7 late deaths, and survival at five years was 76.1%. Although there was a trend for preoperative NYHA class and aortic cross-clamp time to be associated with late survival, the only factor significantly related to late survival was global wall-motion score (p<0.05). Severity of mitral regurgitation and cause of mitral valve disease have been reported as being related to late survival, but we have found no such relationship. Our results indicate that both hospital and late mortality are strongly correlated with preoperative left ventricular function.