Three trials with acyclovir in the treatment of recurrent herpes labialis in the same patient population are reviewed. In the first trial, oral acyclovir capsules, five times per day for five days, were shown to be of significant benefit for some parameters of cutaneous resolution in three successive episodes. Topical formulations were evaluated in two separate trials; 5 percent acyclovir in a modified aqueous cream base exhibited favorable trends, but 5 percent acyclovir in a polyethylene base was ineffective. A high dose of oral acyclovir may offer the most effective method of control of recurrent herpes labialis.