The issue of toxic psychosis has a long history. Up to date definitions according to the ICD-10 and DSM-IV are well described. The terminology, as well as data about incidence, are inconsistent. Beside alcohol induced psychoses, cannabis induced psychotic states are the most common. Psychotic states induced by other substances are less frequent. The pharmacokinetic and pharmacodynamic characteristics of substances are described and can be related with toxic psychoses. Clinical courses are important. Toxic psychoses should be short-term, long-term courses, especially over 6 months, are suspicious from schizophrenic origin. Papers published so far only have a fragmentary character.

Key words: toxic psychoses – classification problems – diagnostics – occurrence – clinical aspects