As part of a survey conducted in six general-hospital departments of internal medicine, in the neighbouring cities of Mannheim and Ludwigshafen (total pop. 470,000), 626 patients in the age range 65 to 80 years, all admitted from private addresses, were screened by means of a standardized questionnaire (Cognitive and Affective Screening of the Elderly--'CASE'). All patients whose scores indicated possible mental abnormality, together with a proportion of those having normal scores, were then examined in greater detail, using the Clinical Psychiatric Interview. Following correction, the screening results indicated a frequency of 30.2% for clinically significant psychiatric disturbance, made up of 9.1% with organic mental disorders and 21.1% with functional mental illness only. These rates are considerably higher than could be expected on the basis of a field study of the background population. One year after hospital discharge, the numbers of deaths and of admissions to long-stay care were established for the whole sample, and in addition, individually matched sub-samples of 100 mentally ill and 100 mentally normal patients were reinvestigated. A second follow-up of the matched sub-samples was undertaken after a further interval of 5.6 years on average. The results of follow-up show that 75% of the identified cases ran a chronic or recurring course, while only a small proportion proved to be transient reactions to physical illness or hospital admission. In general, the psychiatrically ill patients had a relatively unfavourable outcome, even after the effects of age, physical disability and other relevant variables had been controlled for. When compared with the matched group of mentally normal patients, they manifested a 43% excess of mortality, and an increase of 157% in the risk for having to be admitted to long-stay care.