To examine the expression of human immunodeficiency virus type 1 (HIV-1) coreceptors (CCR5 and CXCR4) by monocytic cells within human genital ulcers.Women with primary or secondary syphilis, herpes simplex virus type 1 (HSV-1) or HSV-2 infection, or noninfectious abrasions had a biopsy sample taken from the lesion and contralateral vulva. HIV-1 coreceptor expression on CD3(+) and CD14(+) cells was analyzed by flow cytometry. Real-time reverse-transcriptase polymerase chain reaction was used to assess levels of coreceptor mRNA expression.Women with primary or secondary syphilis or with HSV-1 or HSV-2 infection had significantly increased numbers of CD14(+) cells expressing CCR5 within the genital ulcer. This increase was also noted in the nonulcerated tissue isolated from women with syphilis and in peripheral blood mononuclear cells from women with secondary syphilis. CCR5 mRNA expression was increased in tissue obtained from syphilis lesions.Monocytes recruited to genital ulcer disease (GUD) sites express increased levels of CCR5. This increased expression could account, at least in part, for enhanced HIV-1 transmission in the setting of GUD.