The central register of diabetes mellitus in the SSR keeps records of patients from birth to the age of 14 and 18 years resp. The health institution reports patients on special forms. At the end of the first half of 1988 574 patients from the entire SSR were on record. The incidence of diabetes mellitus in the last years is 6 per 100,000 children and has a slightly rising trend. The prevalence is (to the date of June 30, 1988) 34 in children under 14 years and by age groups it is 6 in children under 4 years, 29 in children under 9 years and 67 in children under 14 years per 100,000 children of the respective age group. This indicates increasing numbers of sick children with advancing age. The register records data from the family-history (incidence of diabetes, risk factors), from the patient's history at the time of the manifestation of the disease and during the period of data collection. The present state is evaluated on the basis of biochemical and clinical results. The state of compensation and quality of cooperation with the patient and parents are interlinked. In 284 families diabetes was present in another or several members (total 413) (genetic predisposition). Before the onset of diabetes mellitus 240 children an acute illness was recorded with a time interval of six weeks (infection and possible damage of islets). In addition to providing basic data for research of the disease, the register helps with dispensarization, statistical work, reports to doctors, inviting patients and planning the needs of sick children.