A tenth version of the International Classification of Diseases (ICD-10) is currently being prepared by the World Health Organization, who called for field trials of suggested guidelines. A field trial of the guidelines for the diagnosis of schizophrenia is presented. There is a consistency with ICD-9-based diagnosis. Schneider's First-Rank Symptoms (FRS) acquire special importance in the suggested guidelines, but caution is necessary in detecting these symptoms in cultures in which socioculturally shared beliefs bear a resemblance to FRS.