The authors investigated various aspects of the international use of and experience with DSM-III through a consultation by mail sponsored by the World Psychiatric Association. The respondents were 175 expert diagnosticians nominated as such by the national psychiatric associations of 52 countries spanning all continents. The United States diagnostic system was used by 72% of the participants, only slightly less than the internationally official International Classification of Diseases, Injuries, and Causes of Death, ninth revision (ICD-9) (77%). Furthermore, DSM-III was perceived to be considerably more useful than the current international classification manual. The leading difficulties encountered with DSM-III involved problematic boundaries or definitions of diagnostic categories and the lack of suitable categories in some cases. The most frequent recommendations offered for the advancement of diagnostic systems included the improvement of patient evaluation procedures, the greater use and refinement of multiaxial diagnosis, and the empirical validation of diagnostic systems.