In the HIV infection, the short time-scale between the HIV-induced cardiovascular events and the onset of antiretroviral therapy elicits a thrombophilic co-factor that worsens the induced atherosclerosis. We compared the factor VIII plasma activity, previously implicated in arterial and venous thrombosis, with a surrogate marker of atherosclerosis, the carotid intima-media thickness, and with the usual atherosclerosis risk factors in 154 HIV infected outpatients. The FVIII plasma activity is significantly associated with the carotid intima-media thickness and, strongly, with blood glucose and triglycerides levels. A raised FVIII plasma activity is an important feature of the metabolic syndrome and a putative co-factor of HAART induced cardiovascular events. Thus the prevention of the HAARTinduced cardio-vascular events should probably not be exclusively focused on atherosclerosis but likewise on the thrombus formation process.