The treatment of herpes simplex virus (HSV) infections in the past has been largely unsuccessful. Introduction of the drug acyclovir has been a positive development. Acyclovir has been extensively studied in the treatment of a a variety of HSV infections in immunocompromised patients and in otherwise healthy patients. The results have shown it to effectively inhibit HSV replication but to have no effect in preventing or eliminating the latent state of the virus. It has been shown to be very effective in certain instances and not so effective in others.