In psychiatry, the new classification of diseases, the ICD-10/ chapter V(F), will be introduced worldwide in the near future. As in the USA in the case of the DSM-III, psychiatrists will have to change their diagnostic procedures from traditional typology to criteria orientation. 83 West German psychiatrists in practice, who were unfamiliar with the use of criteria-oriented diagnostic systems, documented not only the ICD-9 diagnoses of 10,902 depressive patients but also their DSM-III diagnoses. A comparison between the results of the diagnostic distribution of this sample and a smaller sample diagnosed by well-trained interviewers reveals that, to a great extent, systematic mistakes were made, especially by confounding typological and criteria-oriented diagnostic entities. In a vulnerable period of changing diagnostic procedures, such as during the introduction of ICD-10, facilities for training and discussion should be supplied.