OBJECTIVES: Discover if age-, gender-, race-, or income-related disparities in care for coronary artery disease (CAD) exist among Medicare enrollees with supplement plan coverage (i.e. Medigap). METHODS: Data were obtained from UnitedHealth Group's database of AARP Medigap enrollees. Patients were selected into the study if they had one or more medical claims with a diagnosis of CAD from July 1, 2006-June 30, 2007. Logistic regression analyses tested for age-, gender-, race-, or income-related differences in the likelihood of receiving an office visit, coronary angiography, or surgical intervention. The regression models controlled for socioeconomics, health status, type of supplement plan, and residential location. RESULTS: Of the 2.2 million Medigap insureds eligible for the study, 25.4% (570,711) had CAD. Males were 60% (p<0.001) more likely than females to have an office visit, but gender was not a significant predictor for the other services. Patients residing in high-minority neighborhoods were about 8% (p<0.001) less likely to receive any services for CAD. Older individuals were significantly less likely (p<0.001) to have invasive procedures (angiography and surgery). Patients residing in lower-income areas were about 9% (p<0.001) more likely to receive any of the CAD services. Patients with mental health problems were about 45% (p<0.001) less likely to receive any CAD services. Additionally, CAD-related care varied significantly by state of residence and urban versus rural location. Insureds with policies that covered more out-of-pocket costs were more likely to receive an office visit, however, policy type was not a significant predictor for invasive CAD procedures. CONCLUSIONS: Disparities in CAD-related care existed by age, income, and race, but the magnitude was relatively small (about 10%). Larger disparities were found by residential location and for those with mental health problems. AARP and UnitedHealth Group are designing interventions to address these disparities; such interventions will begin in mid-2009.