Most human immunodeficiency virus type 1 (HIV-1) infections are acquired via mucosal surfaces, and transmitted viruses are nearly always macrophage-tropic, suggesting that mucosal macrophages participate in early HIV-1 infection. Mucosal lymphocytes isolated from normal human intestine expressed CD4 (14,530+/-7970 antibody-binding sites [ABSs]/cell), CCR5 (2730+/-1524 ABSs/cell), and CXCR4 (2507+/-1840 ABSs/cell), but intestinal macrophages, which also expressed CD4 (2959+/-2695 ABSs/cell), displayed no detectable CCR5 or CXCR4 ABS. The absence of CCR5 on intestinal macrophages was not due to expression of the Delta32 deletion allele because matched-blood monocytes expressed CCR5. CCR5(+)CXCR4(+) intestinal lymphocytes supported both R5 (BaL) and X4 (IIIB) HIV-1 replication, whereas the CCR5(-)CXCR4(-) macrophages were not permissive to either isolate or other laboratory isolates (ADA and DJV) and primary isolates (MDR 24 and JOEL). In the intestinal mucosa, lymphocytes, not macrophages, are the likely target cell for R5 (and X4) HIV-1 and are the major source of HIV-1 production during early infection.