Clinical psychiatry is confronted with the rapid expansion of the diagnostic facilities of molecular genetics and should therefore reconsider its basic diagnostic procedures. Psychiatric diagnosis should be supplemented by information about birth, developmental history, dysmorphias, congenital malformations, somatic anomalies and family history of both psychopathology and genetic disorders. In addition it should be stressed that psychiatric symptoms in genetic syndromes mostly represent a specific psychopathological phenotype, that does not meet categorical criteria. Recently, several genetic syndromes were found in a number of routinely referred adult patients. In none of the patients genetic analysis was considered previously. Some examples are presented. In all cases the genetic diagnosis had a major impact on the psychiatric diagnosis and treatment. It is concluded that psychiatrists have some knowledge about dysmorphias, relevant developmental issues and basis clinical genetics.