OBJECTIVES: In this ancillary study from MASS III trial, costs and effectiveness were compared between on-pump versus off-pump coronary artery bypass graft surgery in patients with stable multivessel coronary disease with preserved ventricular function at 5-year follow-up. METHODS: Between 2001 and 2006, 308 patients with stable multivessel coronary artery disease and preserved ventricular function were randomized to on-pump CABG (n=153) or off-pump CABG (n=155). The 2 groups were well matched for baseline characteristics. Costs were assessed from the perspective of the Brazilian public health care system. Costs of all cardiovascular events and hospitalizations, medical consultations, diagnostic tests and medications were adjusted for inflation rates for the period until the year 2016. Costs were standardized to 2016 dollars. Health state utilities were assessed using the SF-6D questionnaire. RESULTS: Both groups’ quality of life improved significantly after surgery during follow-up (p < 0.01) compared with baseline, but no differences were found between treatment groups. Although hospital stay (9 ± 2 days vs 6 ± 2 days, p < 0.001) and length of ICU (43 ± 17h vs19,5 ± 17,8h, p < 0.001) of on-pump CABG group were higher than the off-pump CABG group, total costs for the index hospitalization were only $89.19 higher per patient in the on-pump CABG group. Over the next 5 years, follow-up costs were similar between two groups. Nonetheless, cumulative 5-year cost remained only $180.64 higher per patient with on-pump CABG. CONCLUSIONS: In this analysis, QoL was similarly improved in both surgical groups. However, we found no difference in the cost-analysis of on and off-pump procedures.