Brochure Plants: doctors, but also killers, discuss the trend of medicinal plants use which has been going along the humanity since immemorial. It presents origin of their use in historical and geographical context until now, when this trend has been rising again. It emphasizes their indispensability for folk healing, at the beginning of modern medicine, but also in the presence. However, it also points to their possible role as poisons. The brochure highlights attention to the possibilities of reckless combinations and dosages, whose ignorance may result in life-threatening states instead of treatment. Variety of plant substances, their use and representatives are also described. It mentions how plant poisons in moderate doses can be part of our food or medication while some medicinal plants can cause serious poisoning. Only the dose decides if the substance is a poison, the statement of Paracelsus, the famous alchemist of the 16th century, is also the main message of this brochure.