The objectives of this trial were: 1. to evaluate the efficacy of a suppressive course of acyclovir in late pregnancy in women with a history of recurrent genital herpes infection in terms of the number of women undergoing delivery by caesarean section, the number of episodes of clinical herpes recurrences and the number of episodes of asymptomatic virus shedding during treatment; and 2. to evaluate the safety and tolerance of suppressive acyclovir in the woman and her infant.