BACKGROUND: Mentally retarded persons have high prevalences of psychiatric disorders and often receive little professional help for them. MATERIAL AND METHODS: From a total of 48 mentally retarded inhabitants in a local community, 28 were selected on the basis of possible psychiatric problems. A psychiatrist diagnosed the persons and gave advice based on personal observation, contact with caregivers, and all available documentation. RESULTS: The estimated levels of functioning were adjusted for 19 persons. 32 new psychiatric diagnoses were detected. Milieu changes were recommended for 25 persons, and 26 changes in psychotropic medication were recommended. INTERPRETATION: Although the procedure is workintensive, the results justify the described approach.