Malnutrition, weight loss, and body cell mass (BCM) depletion have long been observed in individuals with HIV infection and acquired immunodeficiency syndrome and are associated with increased morbidity and mortality. Nutritional status may be adversely affected by many factors, including inadequate intake, gastrointestinal disturbances, altered nutrient metabolism, and medication-related side effects. Increasing numbers of HIV-infected individuals are exhibiting fat redistribution characterized by any combination of changes including peripheral fat atrophy, visceral or dorsocervical adiposity, or other changes, and these changes have been shown to be associated with increased cardiovascular disease risk. A complete nutrition assessment is key to effective patient management in HIV infection. This review focuses on the evaluation of anthropometry (including BCM and fat redistribution), biochemistries, medication-related issues, medical/social/dietary histories, and physical examination and clinical findings. A discussion of BCM, its significance as a parameter of nutritional status, and methodological issues concerning its measurement by available technologies is presented in light of current research. Methods for assessing fat redistribution are discussed. Recommendations for biochemical assessment and medical, social, and dietary histories are reviewed. Finally, medication-related side effects for common antiretroviral therapies and clinical findings that may affect nutritional status are presented. Clearly, nutrition assessment in HIV infection is a complex process involving many factors.