Background: Constipation is common in Western societies, accounting for 2.5 million physician visits/year in the US. Because many factors predisposing to constipation also are risk factors for cardiovascular disease, we hypothesized that constipation may be associated with increased risk of cardiovascular events. Methods: We conducted a secondary analysis in 93,676 women enrolled in the observational arm of the Women's Health Initiative. Constipation was evaluated at baseline by a self-administered questionnaire. Estimates of the risk of cardiovascular events (cumulative end point including mortality from coronary heart disease, myocardial infarction, angina, coronary revascularization, stroke, and transient ischemic attack) were derived from Cox proportional hazards models adjusted for demographics, risk factors, and other clinical variables (median follow-up 6.9 years). Results: The analysis included 73,047 women. Constipation was associated with increased age, African American and Hispanic descent, smoking, diabetes, high cholesterol, family history of myocardial infarction, hypertension, obesity, lower physical activity levels, lower fiber intake, and depression. Women with moderate and severe constipation experienced more cardiovascular events (14.2 and 19.1 events/1000 person-years, respectively) compared with women with no constipation (9.6/1000 person-years). After adjustment for demographics, risk factors, dietary factors, medications, frailty, and other psychological variables, constipation was no longer associated with an increased risk of cardiovascular events except for the severe constipation group, which had a 23% higher risk of cardiovascular events. Conclusion: In postmenopausal women, constipation is a marker for cardiovascular risk factors and increased cardiovascular risk. Because constipation is easily assessed, it may be a helpful tool to identify women with increased cardiovascular risk. © 2011 Elsevier Inc. All rights reserved.