The human sebocyte model offers several advantages over the current animal models. Foremost among these is the correlation of in vitro activity with clinical results, which was not true for arotinoids in the animal models. It is also possible to study several parameters (total cell number, [3H]thymidine uptake, protein and lipid composition/synthesis, hormone response, receptor regulation, etc.) in the same system. The proliferation of isolated sebocytes is inhibited by retinoids, such as isotretinoin and tretinoin, which are known to be clinically active in human acne. Sebocytes are not responsive to the arotinoid temarotene, which is active in the aforementioned animal models and against dimethylbenz[a]anthracene (DMBA)-induced rat mammary carcinoma but inactive clinically in acne. Additionally, this model is not responsive to etretinate, a compound known to be active in psoriasis but inactive in acne. The in vitro model is, therefore, more predicative of clinical efficacy than the animal models alone.