Whether hepatitis C virus coinfection might accelerate atherosclerosis in HIV-infected individuals is unclear. We examined the relationship of HIV and hepatitis C virus with carotid artery intima media thickness and the presence of carotid plaques in the Women's Interagency HIV Study. Hepatitis C virus infection was not associated with greater carotid artery intima media thickness after adjustment for demographic and traditional cardiovascular risk factors. Further follow-up is needed to clarify whether HIV/hepatitis C virus coinfection may be associated with a greater risk of carotid plaque.