A metabolic syndrome associated with atherosclerosis and cardiovascular disease has been described in HIV-positive individuals. In the present study we investigated whether HIV-positive individuals and CAD (coronary artery disease) patients have similarities in their vascular function and structure. In a case-control study, we compared measurements of carotid artery IMT (intima-media thickness) and brachial artery FMD (flow-mediated vasodilation) in HIV-positive individuals with age- and sex-matched controls with similar risk factors and patients with established CAD. Seventy-one HIV patients, age 42+/-13.9 years (91% male), were compared with 29 CAD patients and 25 controls. HIV patients had higher IMT than controls and similar IMT to CAD patients (0.64+/-0.2 compared with 0.55+/-0.05 and 0.66+/-0.08 mm respectively; F=4.2, P=0.01). Patients taking protease inhibitors had higher IMT (0.69+/-0.2 compared with 0.57+/-0.15 mm; P=0.01), blood pressure, cholesterol and triacylglycerols than those not taking protease inhibtors (P<0.05). In multiple regression analyses, increasing blood pressure (beta: 0.37, P=0.001), glucose (beta: 0.26, P=0.016), cholesterol (beta: 0.24, P=0.033), duration of HIV disease (beta: 0.33, P=0.008) and use of protease inhibitors (beta: 0.27, P=0.04) were the most important determinants of IMT respectively. FMD was associated only with triacylglycerol measurements. Patients with HIV present arterial changes resembling those found in patients with atherosclerotic cardiovascular disease. These vascular changes are closely related to protease-inhibitor-induced changes of metabolic parameters. Thus intensive treatment of these metabolic parameters might retard atherosclerosis in HIV patients.