Objective: Despite various evidence supporting the advantages of multiple arterial grafting, inconsistencies in use of the procedure have resulted in high variability in the acceptance and practice of arterial grafting. The purpose of this study was to assess the effects of an arterial versus venous second grafts on outcomes at 5-year follow-up in the coronary artery bypass grafting population from the Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery (SYNTAX) trial. Methods: Patients (n = 1419) with an arterial graft to the left anterior descending artery and >= 1 other graft were included and divided according to the second graft's type: 2nd-graft-arterial group (n = 456) and 2nd-graft-venous group (n = 963). Five-year outcomes were compared between subgroups. Event rates were estimated with Kaplan-Meier analyses. Propensity-score matching was used, to control for selection bias due to nonrandom group assignment in a 1: 1 manner, resulting in 432 pairs with balanced baseline characteristics. Results: In unmatched groups, the 2nd-graft-arterial group had significantly lower rates of death (8.9% vs 13.1%; P = .02), and composite safety endpoint of death/stroke/myocardial infarction (13.3% vs 18.7%; P = .02), compared with the 2nd-graft-venous group. The rate of major adverse cardiac or cerebrovascular events was similar between groups (22.9% vs 25.5%; P = .30), because it includes the rate of repeat revascularization (12.6% in the 2nd-graft-arterial group vs 9.6% in the 2nd-graft-venous group; P = .10). After propensity-score matching, no statistically significant differences were found between groups. Conclusions: This study reveals comparable 5-year outcomes with arterial and venous conduits as second grafts after an arterial graft anastomosed to the left anterior descending artery. This study demonstrates the multi-institutional variation in patient selection and operator technique with regard to arterial revascularization, although extended follow-up beyond 5 years is required to estimate its impact on long-term outcomes.