Optical coherence tomography (OCT) was used to research skin properties after 5 different pretreatments. Untreated and artificially dried skin was investigated in vivo by OCT. The effects and distribution of moisturizing cream and sunscreen were observed. Additionally, it was possible to visualize the effects of topically applied clobetasol and of UVB radiation on the blood flow of different body sites. Moreover, OCT was used for the characterization of skin elasticity and stages of skin aging and for the evaluation of tattoo-application systems. The present experiments show that OCT is an excellent noninvasive, online method in several fields of dermatological research.