Infection with the human immunodeficiency virus (HIV) frequently is complicated with thrombocytopenia (HIV-Thr) during all stages of the infection. The treatments for autoimmune thrombocytopenic purpura (ITP) are used in HIV-Thr; however, their effects upon the immune status of patients with acquired immunodeficiency syndrome (AIDS) are unknown. Intravenous immunoglobulin (IVIg) is used in patients with ITP and HIV-Thr; however, its usefulness in thrombocytopenic AIDS patients has not been directly addressed. We used a low-dose IVIg regimen (0.04 g/kg per week during five weeks) for the treatment of HIV-Thr complicating AIDS. Thirteen patients received IVIg. We observed a response to IVIg in 13 patients by the end of week one and in 10 patients by the end of week five. Long-term response, evaluated three months after stopping IVIg, was present in four cases. IVIg was well tolerated and no opportunistic infections were observed during the study period. Compared with previous reports, we used 10% of the previously proposed dosage with an important decrease in the cost of treatment. Our results suggest that this low-dose IVIg regimen is a highly effective, nonexpensive alternative in treating HIV-Thr in AIDS. If sustained responses can be obtained with a similar low-dose maintenance regimen, IVIg may be the first choice for the treatment of HIV-Thr in AIDS patients.