Botanical extracts have been used for cosmetic and therapeutic purposes in the form of fresh plants or dried or extracted plant material since ancient times. These extracts are often registered as botanical medicine, also referred to as herbal medicine, phytotherapy, or phytomedicine (1). Today, increasing numbers of patients and consumers are asking for plant-based therapeutic preparations as a complementary dermatologic therapy. Botanical therapies are considered as therapeutic alternatives, as agents of safer choice in comparison to conventional therapy, or sometimes as the only effective therapeutic way remaining to treat a certain skin disease. The cosmetic industry is expanding the use of botanicals by introducing plant extracts, herbs, fl owers, fruits, and seed oleates into their products, prom-ising a gentler, more organic approach to beauty. Botanical-based cosmetics are well ac-cepted by the consumers because they are said to possess the ability to detoxify, hydrate, strengthen, stimulate, relax, and balance the skin and hair. These products with active compounds are collectively referred to as "cosmeceuticals" (2)— a portmanteau of cos-metic and pharmaceutical. Because the use of botanicals in dermatologic products is becoming increasingly pop u-lar, clinicians need to learn about their effi cacy and possible side effects. The present chap-ter mainly focuses on botanicals that have been investigated in clinical trials. However, experimental research on botanicals was also considered to a limited extent when it seemed promising for product development in the near future. The present chapter reviews the results of controlled clinical studies on botanicals used in dermatology. Plant-derived single compounds already established in dermatological therapy such as dithranol, salicylates, or podophyllotoxin are also discussed (Table 3.1). In the following sections, the botanicals are discussed under the dermatological indications where they have been studied or would be primarily indicated according to their mode of action (Table 3.2). Most of the studies on botanical extracts have been performed with topical preparations. Where appropriate, studies with botanical food supplements are con-sidered as well. Finally, the most important limitations for the use of botanicals in derma-tology are outlined. Literature references were obtained between December but also "UV-protection" and "sunscreen." To provide the reader with information on the quality of the studies, each study was classifi ed according to the levels of evidence (LOE) A-D suggested by the U.K. National Health Ser vice (3). In brief, LOE-A is assigned to consistent, randomized, con-trolled clinical trials and cohort studies; LOE-B is assigned to consistent retrospective co-horts, exploratory cohorts, outcome researches, case-control studies, or extrapolations from LOE-A studies; LOE-C is assigned to case-series studies or extrapolations from LOE-B studies; LOE-D is assigned to expert opinions without explicit critical appraisal or based on physiology, bench research, or fi rst principles. Whenever possible, the level of evidence was indicated for each study in squared brackets, for example, as [LOE-A].