The natural history of genital reinfection with herpes simplex virus type 2 (HSV-2) three weeks to one year after initial infection was explored by using a guinea pig model. Intravaginal reinoculation with HSV-2 of animals that had recovered from initial genital infection produced by wild-type or thymidine kinase-deficient HSV-2 produced asymptomatic genital reinfection characterized by high-titered replication of HSV-2 in the vaginal vault. Reinoculation did not result in acute neural infection, as was seen during initial genital herpes, and no evidence of latent infection by the rechallenge strain could be demonstrated. The frequency of recurrences appeared to be established by the initial infection because reinfection did not alter the pattern of recurrent genital herpes. The present study suggest that asymptomatic reinfection may produce a reservoir of communicable virus and that initial infection with a less virulent mutant of HSV-2 may provide protection against subsequent reexposure to wild-type HSV-2.