Idoxuridine (0.1%) in polyvinyl alcohol (1.4%) was applied to recurrent herpes simplex lesions in human beings. Comparison by double-blind placebo control techniques revealed that idoxuridine significantly shortened the healing time of herpes lesions when the medication was applied early in the course of the disease. Background of Disease Herpes simplex virus infections have been a problem to physicians from two standpoints. Herpes simplex keratitis has been a major cause of blindness in the United States for many years, particularly since gonorrheal ophthalmia became a rarity. Recurrent herpes simplex skin infections have always been frustrating for the physician. The single attack has not usually been serious. However, the large number of people afflicted often have frequent attacks. These clinical facts, as well as research literature, force admissions that all previously available therapy, when subjected to critical, controlled evaluation, has proved ineffective. (The less common types of herpes, such as primary herpetic