Participants will be seen in the clinic once a month for 8 months. At these visits, source partners will 1) return unused study medication and the completed diary card; 2) discuss any adverse drug side effects experienced in the last month; 3) review medications other than the study drug taken in the last month; 4) undergo counseling on safer sex practices, transmission of genital herpes, and recognizing signs and symptoms of a first episode of genital herpes; and 5) review symptoms and recurrences of genital herpes experienced during the last month. During the final visit, they will also provide a blood sample for routine testing and possible use in future studies. Susceptible partners will 1) have a blood sample drawn for HSV testing; 2) undergo safer sex counseling; 3) review any symptoms experienced over the last month; 4) be interviewed about sexual exposure and practices; and 5) return the completed diary card.