To investigate the importance of the payer in the utilization of in-hospital cardiac procedures, we examined the care of 37 994 patients with Medicaid, private insurance, or no insurance who were admitted to Massachusetts hospitals in 1985 with circulatory disorders or chest pain. Using logistic regression to control for demographic, clinical, and hospital factors, we found that the odds that privately insured patients received angiography were 80% higher than uninsured patients; the odds were 40% higher for bypass grafting and 28% higher for angioplasty. Medicaid patients experienced odds similar to those of uninsured patients for receiving angiography and bypass, but had 48% lower odds of receiving angioplasty. In addition, the odds for Medicaid patients were lower than for privately insured patients for all three cardiac procedures. These findings suggest that insurance status is associated with the utilization of cardiac procedures. Future studies should determine the implications these findings have for appropriateness and outcome and whether interventions might improve care.