Talarozole (formerly R115866) is a new highly potent and selective azole derivative, which inhibits cytochrome-P450-dependent all-trans-retinoic acid catabolism by blocking the cytochrome P450 enzyme isoform CYP26, a retinoic acid hydroxylase. It is in clinical development for the treatment of psoriasis and acne. However, no local pharmacokinetic data on the diffusion behaviour of talarozole in the skin itself are available. As topical application might be an interesting alternative to oral therapy because of the reduced systemic side effects. The distribution of talarozole within the skin was investigated: 80% was located in the epidermis, while the remaining 20% was found in the dermis. The epidermal concentration of talarozole achieved after a single topical application was sufficiently high to enable the potential induction of local retinoid-like effects.