This chapter provides an overview of our present knowledge on mushroom toxins, and discusses the toxins in order of importance. The chapter includes: information on the mushroom species producing the toxin; chemistry and detection of the toxin; and the medical impact of the toxin, i.e., the symptoms produced, and the appropriate treatment of the poisoning. The information is based on several reviews (Spoerke and Rumack, 1994; Faulstich and Wieland, 1992; Wieland and Faulstich, 1983), which may be consulted for more details, as well as on data taken from the current literature.