Nutritional status and some iron metabolism parameters of acute phase response (APR) positive and APR-negative AIDS patients were studied. Twenty-nine AIDS patients were submitted to 24h food intake recall, anthropometry, and albumin, C-reactive protein (CRP), hemoglobin, ferritin, and total iron binding capacity (TIBC) measurements. Infection plus serum CRP > 7 mg/dl were criteria for APR presence. Protein-energy malnutrition (PEM) was ascertained by body mass index (BMI) lower than 18.5 kg/m2 and height-creatinine index (HCI < 70%). PEM (77.8 vs 40%) and pulmonary tuberculosis (44. 4 vs 9.5%) were more frequent in APR-positive patients, which also had lower serum albumin (3.7 +/- 0.9 vs 4.3 +/- 0.9 g/dl), TIBC (165. 8 +/- 110.7 vs 265.9 +/- 74.6 mg/dl) and blood hemoglobin (10.5 +/- 1. 8 vs 12.6 +/- 2.3g/dl). Iron intake was similar between groups; however, serum ferritin levels (median, range) were higher among APR-positive (568, 45.3-1814 vs 246, 18.4-1577 ng/ml) patients. HIV-positive adults with systemic response to invading pathogens showed worse nutritional status than those APR-negative. In APR-positive AIDS patients, anemia appears to be unrelated to recent iron intake.