Cyclosporine (CSA) is an effective immunosuppressive agent and is used in tissue transplantation. The present investigation was undertaken to determine the effect of topical delivery of CSA on allergic contact dermatitis in guinea pigs, Topical 15% CSA in an azone (l‐dadecychlohepatan‐2–one)containing vehicle blocked local elicitation in previously dintrochlorobenezene(DNCB) sensitized animals that received a single topical application just prior to elicitation. Elicitation was not blocked at a distant site, indicating a local effect of topical CSA. In contrast, topical CSA when applied twice daialy for a total of 5 applications during sensitization only, did not block subsequent elicitation. These experiments suggest that cyclosporine tna be beneficial in the therapy of human contact dermatitis, as well as other T cell mediated derma