In the Centre of Diabetes and Metabolic Disorders of Berlin, G.D.R., a computer-aided care system has been used since 1974, aiming at relieving physicians and medical staff from routine tasks and rendering possible epidemiological research on an unselected diabetes population of a defined area. The basis of the system is the data bank on diabetics (DB), where at present data from approximately 55,000 patients are stored. DB is used as a diabetes register of Berlin. On the basis of standardised criteria of diagnosis and therapy of diabetes mellitus in our dispensary care system, DB facilitates representative epidemiological analyses of the diabetic population, e.g. prevalence, incidence, duration of diabetes, and modes of treatment. The availability of general data on the population or the selection of specified groups of patients serves the management of the care system. Also, it supports the computer-aided recall of type II diabetics, treated either with diet alone or with diet and oral drugs. In this way, the standardised evaluation of treatment strategies in large populations of diabetics is possible on the basis of uniform metabolic criteria (blood glucose plus urinary glucose). The system consists of a main computer in the data processing unit and of personal computers in the diabetes centre which can be used either individually or as terminals to the main computer. During 14 years of experience, the computer-aided out-patient care of type II diabetics has proved efficient in a big-city area with a large population.