Type I interferon (IFNα/β) plays a complex role in HIV-1 infection and has been proposed alternately to have roles in either disease protection or progression. Although IFNα/β plays crucial roles in regulating monocytes and dendritic cells, responsiveness of these cells to IFNα/β in HIV-1 infection is poorly understood. We report significant defects in IFNα/β receptor (IFNα/βR) expression, IFNα signaling, and IFNα-induced gene expression in monocytes from HIV-1–infected subjects. IFNα/βR expression correlated directly with CD4⁺ T-cell count and inversely with HIV-1 RNA level and expression of CD38 by memory (CD45RO⁺) CD8⁺ T cells, a measure of pathologic immune activation in HIV-1 infection associated with disease progression. In addition, monocytes from HIV-1–infected persons showed diminished responses to IFNα, including decreased induction of phosphorylated STAT1 and the classical interferon-stimulated gene produces MxA and OAS. These IFNα responses were decreased regardless of IFNα/βR expression, suggesting that regulation of intracellular signaling may contribute to unresponsiveness to IFNα/β in HIV-1 disease. Defective monocyte responses to IFNα/β may play an important role in the pathogenesis of HIV-1 infection, and decreased IFNα/βR expression may serve as a novel marker of disease progression.