The special literature of the last two decades has mentioned repeatedly the occurrence of a "malignant neuroleptic syndrome", a severe, and not too rare complication of therapy with neuroleptic drugs. The authors make an analysis of 17 cases, and discuss the conditions of the development, the symptomatology and the treatment of the malignant neuroleptic syndrome. Due to the fact that the use of neuroleptics has been introduced in other fields of medicine the authors consider that information of physicians of all specialties with regard to this severe complication of neuroleptic therapy is useful.