The safety of repeat coronary revascularization using the internal mammary artery (IMA) as a conduit was examined in patients undergoing repeat revascularization between January 1988 and June 1991. The 71 patients in whom the IMA was used as one of the conduits were compared with 57 patients in whom only vein grafts were used. Patients undergoing IMA grafts were likely to have more vessels revascularized. Nevertheless, there were no significant differences in outcome between the two groups as measured by complications or period of hospitalization. In a multivariate analysis, the only independent predictor of poor outcome was emergency surgical treatment. The current study would indicate that IMA grafts are safe in the setting of repeat coronary revascularization.