The chewing of leaves of the khat shrub is common in certain countries of East Africa and the Arabian peninsula, and some khat users are subject to psychic dependence on this stimulant. Recently, important progress has been made in understanding the pharmacological basis for the effects of khat. It is now known that the CNS stimulation is mainly due to the presence of the alkaloid cathinone in the leaves, and the results of various in vitro and in vivo experiments indicate that this substance must be considered a "natural amphetamine." In recent years, several cases of khat intoxication observed in the USA and in Great Britain have been described in the literature. In view of these developments, the khat habit and its health effectsare described, and the possibilities for the treatment of acute khat intoxication are discussed.