Objective To compare mortality, nonfatal coronary heart disease (CHD), and congestive heart failure (CHF) risk across BMI categories in white, African American, and Hispanic women, with a focus on severe obesity (BMI ≥ 40), and examine heterogeneity in weight-related CHD risk. Methods Among 156,775 Women's Health Initiative observational study and clinical trial participants (September 1993-12 September 2005), multivariable Cox models estimated relative risk for mortality, CHD, and CHF. CHD incidence was calculated by anthropometry, race, and cardiovascular risk factors (CVRF). Results Mortality, nonfatal CHD, and CHF incidence generally rose with BMI category. For severe obesity versus normal BMI, hazard ratios (HRs, 95% confidence interval) for mortality were 1.97 (1.77-2.20) in white, 1.55 (1.20-2.00) in African American, and 2.59 (1.55-4.31) in Hispanic women; for CHD, HRs were 2.05 (1.80-2.35), 2.24 (1.57-3.19), and 2.95 (1.60-5.41) respectively; for CHF, HRs were 5.01 (4.33-5.80), 3.60 (2.30-5.62), and 6.05 (2.49-14.69). CVRF variation resulted in substantial variation in CHD rates across BMI categories, even in severe obesity. CHD incidence was similar by race/ethnicity when differences in BMI or CVRF were accounted for. Conclusions Severe obesity increases mortality, nonfatal CHD, and CHF risk in women of diverse race/ethnicity. CVRF heterogeneity contributes to variation in CHD incidence even in severe obesity. Copyright © 2012 The Obesity Society.