BACKGROUND: The effects of various cardiovascular diseases on the risk of venous thromboembolism (VTE) are not well defined. To gather more information, we performed a hospital-based case-control study to evaluate the effects of major cardiovascular diseases on the risk of VTE. METHODS: We identified all incident cases of VTE needing hospitalization and anticoagulant therapy between January 1990 and December 2002 in a large tertiary hospital. Each case was matched with up to 4 controls, randomly selected from inpatients who were not hospitalized due to any of the exposures, on age, sex, calendar time and veteran/nonveteran status. RESULTS: This study comprised 173 cases of VTE and 546 matched controls. The adjusted odds ratio (OR) of VTE was significant among patients with peripheral atherosclerotic diseases (OR 7.1, 95% confidence interval [CI] 1.4-34.4), and nondebilitating cerebrovascular diseases (OR 2.5, 95% CI 1.4-4.7). Other independent risk factors for VTE included a body mass index>or=25.0 kg/m2, current estrogen use, a history of hyperlipidemia and varicose veins. CONCLUSION: Peripheral atherosclerotic disease and nondebilitating cerebrovascular disease are important risk factors for VTE. Patients with these diseases should therefore be frequently evaluated for the possible coexistence of VTE and, if appropriate, should be given prophylaxis. Failure to take into account the potential confounding effects of these diseases may also result in an erroneous estimate of the effect of drug exposures on the risk of idiopathic VTE.