Genital herpes simplex virus (HSV-1 and HSV-2) infection is an ulcerative, lifelong, recurring sexually transmitted disease of increasing epidemiologic worldwide importance. Transmission occurs by close skin contact, usually during asymptomatic virus shedding. The virus persists in the dorsal root ganglion where it is not accessible to the host's immune system. The most important risk factor is a person's number of lifetime sex partners. The more extensive first-episode infection is followed by milder recurrences. Recurrence rates differ greatly. The diagnosis is made clinically, microbiologically, and serologically. There are several virostatic agents available for treatment.