In order to analyze the nutritional status of HIV infected patients and the involvement of the tumour necrosis factor-alpha (TNF-alpha) and its soluble receptors (sTNFRI and sTNFRII) in such an status, forty HIV infected patients, with no associated systemic opportunist infections, were prospectively followed for eight months. From each patient the following were obtained: clinical history, dietetic survey, anthropometric measurements, CD4+ T lymphocyte/mm3 count, HIV load, and serum concentration of TNF and sTNFRI and sTNFRII. Patients showed a nutritional disorder which involved mainly the fat compartment (mean tricipital skin fold 9.8 +/- 4.2 mm, that is, 65.7 +/- 27.4% of the ideal fold), associated with a hypocaloric intake (mean daily intake 1,659.5 +/- 543.0 kcal), with normal proportions of the different organic principles. Serum concentrations of TNF (87.9 +/- 79.2 vs 8.7 +/- 6.1 pg/ml, p = 0.048) and its receptors, sTNFRI (6.1 +/- 2.6 vs 1.0 +/- 0.8 pg/ml, p < 0.001) and sTNFRII (41.9 +/- 18.6 vs 6.3 +/- 3.6 pg/ml, p < 0.001) were significantly higher than those detected in a sample of ten healthy controls. No correlation was found between nutritional alterations and concentrations of TNF or its receptors, viral load, and counts of CD4+ T lymphocytes/mm3. Seventeen patients completed the follow-up period. During this period, no significant modifications in the analyzed parameters were observed: tricipital skin fold, arm circumference, serum concentrations of albumin or transferrin, concentrations of tumoral necrosis factor or its receptor and caloric intake. The conclusion is that, despite the detected nutritional alterations in the nutritional status and those in the TNF/receptor system, our data no support and interrelationship between them.