In the last several years, the biologic modification of the immune system has become one of the therapeutic alternatives in medicine. The use of interferon alpha has resulted in both antineoplastic and antiviral effects in patients with AIDS-associated Kaposi's sarcoma. Trials currently underway will determine whether or not this drug, either alone or in combination with zidovudine, is of overall value to patients with early stages of HIV-1 infection. Hematopoietic growth factors, GM-CSF and erythropoietin in particular, offer new hope that the bone marrow suppressing toxicities of certain therapeutic agents such as zidovudine and ganciclovir can be ameliorated, thus allowing the more aggressive use of these important medications. Although a variety of non-biologic immunomodulators have been evaluated in patients with HIV-1 infection, none thus far has shown the clear clinical advantage that has been demonstrated for zidovudine and a variety of clinical trials continue in this area. The area of immunologic reconstitution, although promising in concept, has been disappointing in practice, even in combination with zidovudine. Recent approaches to immunomodulation have included active immunotherapy involving immunization of HIV-1 infected individuals with either inactivated virus or recombinant HIV-1 proteins. Continued investigation of the role of immunomodulation in the therapy of patients with HIV-1 infection should be of value, not only in developing better therapies for patients with HIV-infection, but also in helping develop a better understanding of the nature of the immunologic defects seen in the context of this infection.