A total of 156 patients with frequently recurring genital herpes were enrolled in a randomized, double-blind, one-year trial comparing long-term suppressive and intermittent oral acyclovir therapy with placebo in the management of recurrent genital herpes. Subjects received either suppressive treatment with acyclovir, 400 mg twice daily for one year, and 200 mg five times per day for five days, for short-term treatment of recurrences; intermittent treatment with placebo, twice daily for one year, and oral acyclovir, 200 mg five times per day for five days, for short-term treatment of recurrences; or treatment with placebo, twice daily for one year, and five times per day for five days for short-term treatment of recurrences. Median time to first recurrence was 250 days for the suppressive group, 28 days for the intermittent group, and 23 days for the placebo group (p = 0.001). The median number of days per month with active disease was 0.32 for the suppressive group, 4.18 for the intermittent group, and 4.72 for the placebo group (p less than 0.001), with a median recurrence rate per 30-day treatment period of 0.08 recurrences/patient in the suppressive group, 0.70 in the intermittent group, and 0.74 in the placebo group (p less than 0.001). Median duration of recurrence was 5.0 days in the suppressive group compared with 6.0 days in the combined intermittent acyclovir plus placebo group (p = 0.001), and was reduced from 7.0 to 6.0 days when intermittent acyclovir treatment was compared with placebo treatment (p = 0.05). Daily administration of oral acyclovir for one year is superior to intermittent or placebo treatment in the management of patients with frequently recurring genital herpes.