Background: The definition and prognostic utility of the metabolic syndrome remain controversial. Analyses in predominantly healthy populations suggest that the International Diabetes Federation (IDF) definition identifies more men with metabolic syndrome than the Adult Treatment Panel III (ATP III) criteria, with little difference among women. Whether the IDF definition identifies a greater prevalence of the metabolic syndrome than the ATP III definition in women with coronary artery disease (CAD) is unknown. Methods: We compared the prevalence and prognostic utility of both definitions of the metabolic syndrome in postmenopausal women with angiographic CAD enrolled in the Women's Angiographic Vitamin and Estrogen Trial (WAVE). We excluded 51 of 423 women enrolled (12%) who had missing data for components of the metabolic syndrome. Results: Mean age was 65.3 ± 8.4 years, 70% were white, mean body mass index (BMI) was 30.5 ± 6.0 kg/m2, mean waist circumference was 96.2 ± 12.9 cm, 89% had hypertension by history or elevated blood pressure, 58% had diabetes or hyperglycemia, 54% had low high-density lipoprotein cholesterol (HDL-C), and 44% had hypertriglyceridemia. Metabolic syndrome prevalence was 70% and 74% by ATP III and IDF criteria, respectively; 68% met criteria for both definitions. Classification between the two criteria was not affected by ethnicity or age. Incident cardiovascular events were similar in both metabolic syndrome classifications. Conclusions: Among postmenopausal women with angiographic CAD, the metabolic syndrome is very prevalent. The IDF modification of the ATP III definition only identifies a small additional number of women as having metabolic syndrome, independent of ethnicity or age, and provides little additional prognostic information. © 2008 Mary Ann Liebert, Inc.