Vitamin D metabolites, immunologic, virologic, and clinical parameters, and survival time were determined in 22 asymptomatic human immunodeficiency virus (HIV)-infected patients (CDC stage II/III), 31 symptomatic HIV-infected patients (CDC stage IV), and 28 HIV-seronegative controls. Significantly lower serum levels of 1,25-vitamin D (1,25D) were found in symptomatic patients (median, 34 pg/mL; 25th-75th percentile, 21-45) compared with controls (49 pg/mL; 39-59) and asymptomatic patients (45 pg/mL; 42-50). In HIV-infected subjects, the serum level of 1,25D was positively correlated with CD4+ cell counts in peripheral blood (r = .35, P < .05) and negatively correlated with the level of serum neopterin (r = -.36, P < .01). HIV-infected patients with abnormally low 1,25D (< 25 pg/mL) also had shorter survival times than other HIV-infected subjects (P < .01). Low 1,25D levels did not appear to be related to vitamin D deficiency.