Malnutrition and wasting are common in patients with HIV infection. Nutritional needs vary with the stage of HIV disease. Severe weight loss is associated with increased mortality in patients with AIDS and is multifactorial in development. Possible causes of weight loss include decreased food intake due to oral or GI pathology or anorexia, nutrient malabsorption, and systemic infections. Severe malabsorption is limited to patients with advanced HIV disease with CD4+ cell counts < 100 and usually < 50 cells/microliters. The spectrum of GI pathogens continues to broaden. For hypermetabolic patients, evaluation for systemic infection followed by effective antiinfective treatment is critical. For nonhypermetabolic patients, a variety of metabolic and endocrinological abnormalities may be present. It is important to recognize that micronutrient deficiencies often accompany macronutrient deficits. Providing appropriate nutritional support to patients with AIDS is fundamental to optimal medical care. Overall indications for nutritional support in a patient with AIDS are the same as in any other chronic disease. Nutritional repletion is well documented, and there are a variety of approaches to achieving appropriate intake, including volitional (megestrol or dronabinol therapy) and nonvolitional (feeding tubes and total parenteral nutrition). Parenteral nutrition should not be undertaken without preset limits. The value of nutritional pharmacology with supraphysiological doses of micronutrients has not been established.