Ever since the first report in 1967 of the association of herpes simplex virus type 2 (HSV-2) with urogenital infections, we have noted the occasional isolation of HSV-1 from such sites. Our most recent results of the typing of HSV isolates from 527 individuals with urogenital infections show that 10.9% of such infections in females and 3.4% in males are caused by HSV-1. We describe here the acquisition of a primary oral HSV-1 infection in a male after orogenital contact with his wife who had a primary genital HSV-1 infection, probably as a result of sexual contact with another male partner. The various modes of acquisition and spread of genital HSV-1, including nonvenereal routes, are reviewed. It is suggested that the influence of the microenvironment of the female genital tract on the selection of variants of microorganism--viruses, bacteria, etc--requires concerted study.