Macrophages infected with human immunodeficiency virus (HIV) can be stimulated as a result of secondary infections. The effect of stimulation of HIV-1-infected monocyte-derived macrophages on HIV-1 production by these cells was studied. Exposure of macrophages to phorbol 12-myristate 13-acetate or to opsonized Escherichia coli, Staphylococcus aureus, or zymosan resulted in a decrease in HIV production. HIV production was inversely related to the degree of stimulation, measured as lucigenin-enhanced chemoluminescence. The production of reactive oxygen intermediates, however, did not seem to be the direct cause of the diminished HIV production, since oxygen-radical scavengers did not prevent the decrease in HIV production. Furthermore, oxygen-radical scavengers did not affect HIV production by nonstimulated macrophages. These results indicate that activation signals have an opposite effect and reactive oxygen intermediates have no effect on HIV production in macrophages compared with the effect described in T cells.