To the Editor: In recent years there has been a steady increase in the study of antiviral agents for the treatment of common viral infections. Dunkle et al. (Nov. 28 issue)1 reported on a study involving the use of acyclovir in the treatment of the primary varicella–zoster infection, chickenpox. In their well-designed study, they clearly showed that the normal children treated with acyclovir had a reduction in the duration and severity of disease. They further concluded that “since acyclovir treatment interferes with neither the pre-eruption pathophysiology of primary varicella–zoster virus infection nor the subsequent immune response, treatment of chickenpox is.