Worldwide, herpes simplex virus type 2 (HSV-2) infection is the biggest cause of genital ulcer disease, and is responsible for the majority of cases of genital herpes. The risk of transmitting genital herpes to a partner is one of the leading causes of psychological distress for those with the disease. Antiviral compounds available for the treatment of genital herpes are known to reduce clinical recurrence rates and HSV shedding. This understanding provided impetus for a randomized, placebo-controlled study to assess the ability to interrupt transmission of HSV using oral valaciclovir therapy (500 mg, once daily). The study enrolled 1484 immunocompetent, heterosexual, monogamous couples in stable relationships where both partners were aware of the source partner's infection and the source partner had symptomatic genital herpes. Valaciclovir reduced the risk of transmitting HSV-2 infection by 48%. Furthermore, valaciclovir reduced the risk of clinical disease in the susceptible partner by 75%. As a result, the International Herpes Management Forum (IHMF) now recommends that physicians offer suppressive valaciclovir therapy to immunocompetent individuals concerned about transmitting genital herpes to a heterosexual partner, and advises safer sex behaviour, including the use of condoms, to prevent genital herpes transmission.