We have measured the fatty acid (FA) composition of erythrocyte membranes and plasma anti-oxidants in HIV+ patients. Saturated FA are higher and poly-unsaturated FA lower than in controls (P = 0.02). Selenium (Se) is lower in patients less than 400 CD4 cells/mm3 (P = 0.002). Vitamin A is lower in the HIV+ regardless of the CD4 cell count. Se and vitamin A are correlated to nutritional markers (body mass index and albumin).