1-Dodecylazacycloheptan-2-one (Azone) is a new agent that enhances the percutaneous penetration of a number of different chemicals. BVDU and FEAU were evaluated for their potential efficacy in the treatment of cutaneous herpes simplex virus infections by in vitro studies through hairless mouse skin. This study demonstrates the value of penetration enhancing agent (Azone) and the need for a predictable evaluations in the development of topical antiviral agents.