Abstract: The present invention provides novel methods for the treatment of retroviral infection, particularly HIV disease. According to the present invention, human HIV infected hosts were selected who had been on a stable dose of an anti-retroviral agent, such as zidovudine, for up to two years prior to administration of the ribosomal inhibiting protein trichosanthin, and who had failed anti-retroviral therapy, as manifest by decrease in CD4+ cells on at least two serial measurements, or loss of over 50 CD4+ cells/mm.sup.3 /year. These patients remained on the same dose of anti-retroviral agent (AZT or ddI) and received trichosanthin, 1.2 mg weekly, then monthly. A significant number of patients demonstrated improved CD4+ cell counts following administration of trichosanthin as compared to CD4+ cell counts prior to adminstration of the drug.