In 37 intravenous drug users (IVDUs) in the first stages of HIV-infection (17 in stage II and 20 in stage III according to CDC), compared with 32 IVDUs HIV-negatives, we found a significant decrease in circulating leucocytes (p less than 0.01), lymphocytes (p less than 0.005), platelets (p less than 0.005), serum albumin (p less than 0.005), and C3 (p less than 0.02) and significant increase in serum gammaglobulins (p less than 0.0005) and IgG (p less than 0.0005). On the other hand no difference was observed in hemoglobin and in IgA levels; nevertheless an inverse relationship between serum IgA and CD4+ lymphocytes was present in HIV-positive (HIV+) patients (r = -0.34; p = 0.04). This observation agrees with that is observed in the advanced stages of HIV-infection, which presents an increase in IgA serum levels. In these stages this fact could be due to a decrease of secretory IgA, with a deficient barrier effect; the consequent recirculation of intestinal antigens should enhance the antibody production, as well as serum IgA. In the IVDUs HIV-infected a reverse correlation between albumin serum levels and the length of HIV-positivity (r = -0.44; p = 0.008) and a direct correlation between albumin serum levels and circulating CD4+ lymphocytes (r = 0.37; p = 0.05) were present. There was no direct linear relationship between albumin serum levels and creatinine, on the contrary to what was observed in the control group. The decrease of albumin levels could have a prognostic value as in other clinical conditions, in which it is associated with a higher mortality risk. Many factors could act to decrease albumin levels, but the most important one is perhaps the malnutrition of HIV-infected patients that can also be present in the first stages of infection, negatively influencing the associated immunodeficiency.