The effect of lipid-based parenteral nutrition was assessed in eight patients with AIDS and weight loss of 10% or greater. All patients received home parenteral nutrition consisting of a lipid-based system with 50% of nonprotein calories given as fat. Measurements were made of body weight, serum albumin, and immune function as assessed by mitogen responses, P24 antigen levels and T-cell counts. Over a period of 2 months, weight gain and improved well-being were noted in all patients. An improved in vitro lymphocyte mitogenic response to phytohemagglutinin and to concanavalin A was also noted. No change in T-cell subsets was observed. Viral cultures and P24 serum levels also remained unchanged. Lipid-based parenteral nutrition is safe and probably efficacious in AIDS. (Journal of Parenteral and Enteral Nutrition 16:165-167, 1992).