In order to evaluate the efficacy of intravenous immunoglobulin (IVIG) in the early stages of HIV infection (patients without AIDS or AIDS related complex) a prospective controlled open trial was conducted in 36 patients (age 6-19 years) with haemophilia. Eighteen patients received 0.3 g/kg IVIG at two week intervals; 18 patients served as controls. Major criteria for the evaluation were progression of HIV disease assessed by the modified Brodt/Helm classification, number of infectious events and HIV associated thrombocytopenia, and the CD4+ T cell count. After 24 months of evaluation seven patients in the IVIG group and five patients in the control group deteriorated according to their staging, with one patient in each group developing AIDS. Thrombocytopenia and infectious events, but no severe bacterial infections, occurred in both groups in similar numbers. The absolute CD4+ T cell count decreased by 284/microliters in the IVIG group and by 143/microliters in the control group respectively (mean values). The statistical analysis of these criteria did not reveal any significant difference. In conclusion, IVIG was not effective in the early stages of HIV infection in patients with haemophilia. IVIG did not slow down the progression of HIV disease and did not prevent the development of an immunodeficiency as assessed by the CD4+ T cell count.