CD4(+) T cells and macrophages are the primary target cells for HIV in vivo, and antiretroviral drugs can vary in their ability to inhibit the infection of these different cell types. Resistance pathways to the HIV integrase inhibitor raltegravir have previously been investigated in T cells. Primary raltegravir resistance mutations, most often at integrase amino acid position 148 or 155, afford some resistance to the drug. The acquisition of pathway-specific secondary mutations then provides higher-level resistance to viruses infecting T cells. We show here that during macrophage infection, the presence of a single primary raltegravir resistance mutation (Q148H, Q148R, N155H, or N155S) is sufficient to provide resistance to raltegravir comparable to that seen in viruses expressing both primary and secondary mutations in costimulated CD4(+) T cells. These data implicate macrophages as a potential in vivo reservoir that may facilitate the development of resistance to raltegravir. Notably, the newer integrase inhibitor MK-2048 effectively suppressed the infection of all raltegravir-resistant viruses in both T cells and macrophages, indicating that more recently developed integrase inhibitors are capable of inhibiting infection in both major HIV cellular reservoirs, even in patients harboring raltegravir-resistant viruses.