Ciclosporin is a lipophilic cyclic polypeptide with powerful immunosuppressive and immunomodulatory properties that has been used in veterinary medicine for two decades. It is a calcineurin inhibitor whose principal mode of action is to inhibit T cell activation. The drug is principally absorbed from the small intestine and is metabolised in the intestine and liver by the cytochrome P450 enzyme system. Ciclosporin is known to interact with a wide range of pharmacological agents. Numerous studies have demonstrated good efficacy for the management of canine atopic dermatitis and this has been a licensed indication since 2003. In addition to the treatment of atopic dermatitis, it has been used as an aid in the management of numerous other dermatological conditions in animals including perianal fistulation, sebaceous adenitis, pododermatitis, chronic otitis externa and pemphigus foliaceus. This article reviews the mode of action, pharmacokinetics, indications for use and efficacy of ciclosporin in veterinary dermatology.