OBJECTIVE: We sought to compare early and midterm clinical outcomes in patients receiving a right internal thoracic artery or a radial artery as the second arterial conduit for myocardial revascularization. METHODS: Data prospectively collected for all patients who underwent coronary artery bypass surgery between April 1996 and May 2001 and who received both a left internal thoracic artery graft and either a right internal thoracic artery (n = 336) or a radial artery graft (n = 325) were analyzed. Patients in the radial artery group were older, with a greater body mass index, poorer ejection fraction, greater prevalence of diabetes, and higher New York Heart Association class than those in the right internal thoracic artery group. RESULTS: Odds ratios for perioperative myocardial infarction, atrial fibrillation, postoperative transfusion, and intensive care unit stay all showed a statistically significant benefit in the radial artery group compared with results in the right internal thoracic artery group (P <or=.05). Survival estimates at 18 months for patients who received right internal thoracic artery and radial artery grafts were 98.4% and 99.7%, respectively (hazard ratio, 0.25; 95% confidence interval, 0.06-1.10; P =.07). Estimates for survival free from any cardiac-related event or death in the right internal thoracic artery and radial artery groups were 92.3% and 97.8%, respectively (hazard ratio, 0.37; 95% confidence interval, 0.16-0.84; P =.02). A multivariate Cox regression model showed a stronger protective effect of a radial artery graft (hazard ratio, 0.25; 95% confidence interval, 0.12-0.51; P <.0001). CONCLUSION: Early and midterm outcomes of myocardial revascularization with 2 arterial grafts are better if the radial artery is used for the second graft rather than the right internal thoracic artery, assuming that the left internal thoracic artery is used for the first arterial graft.