We prospectively studied the relationship between dietary intake at baseline and the development of AIDS over 6 years in a population-based sample of 296 human immunodeficiency virus (HIV)-seropositive men. Nutrient intake was assessed before HIV serostatus was known. Subjects diagnosed with AIDS at baseline or during the 1st year were excluded. After adjustment for baseline CD4 T-lymphocyte count, HIV symptoms, and other risk factors, no nutrients were significantly associated with AIDS. However, when the continuous CD4 count and HIV symptom variables were replaced with a single binary health status variable, the hazard of AIDS decreased as consumption increased for all 11 micronutrients; this relationship was statistically significant for iron, vitamin E, and riboflavin and approached significance for vitamins C, thiamine, and niacin. Higher intake of all 11 micronutrients was associated with higher CD4 counts at baseline, and was significantly so for six of them. Daily multivitamin use was associated with a reduced hazard of AIDS [hazard ratio (HR) = 0.7; 95% confidence interval (CI) = 0.5, 1.0] and a significantly reduced risk for low CD4 counts at baseline (HR = 0.6, 95% CI = 0.4, 0.9). Additional studies are needed to determine whether dietary intake modifies the rate of developing AIDS in those who are HIV seropositive.