Patients with frequent recurrences of genital herpes were treated with oral acyclovir tablets, 800 mg, or placebo once daily for two years. Confirmed recurrences for all patients were treated with acyclovir capsules, 200 mg orally five times per day, for five days. Of 46 patients enrolled, 18 of 22 acyclovir recipients and 14 of 24 placebo recipients completed two years of study. Patients receiving acyclovir experienced a mean of 0.184 recurrences/month compared with a mean of 0.977 recurrences/month for patients receiving placebo (p less than 0.0001). A total of 28 percent of acyclovir recipients and no placebo recipients remained free of recurrences for two years. The low rate of recurrences in the acyclovir group remained consistent throughout the study. No serious clinical or laboratory abnormalities associated with acyclovir were observed. The 800-mg acyclovir tablet given daily was well-tolerated and effective for two years in the management of recurrent genital herpes.