Introduction. The Russian Federation continues to experience population aging. Health indicators deteriorate with age, and most people past working age suffer from multiple chronic diseases, increasing their need for medical care. In the context of a changing demographic situation, hospital-replacing technologies (day hospitals) make it possible to rationally use health care resources, expand the volume and increase the availability of medical care of patients older than working age. Purpose. To study the composition of patients over the working age treated in day hospitals of medical organizations providing care in inpatient and outpatient settings in the Russian Federation. Materials and methods. Data from industry statistical observation form No. 14ds, "Information on the activities of day hospitals of medical organizations" for the Russian Federation for 2016–2025 was analyzed. This data covered the number of patients over the working age treated in day hospitals of medical organizations providing inpatient and outpatient care, and the average duration of their treatment. Since 2025, industry statistical observation form No. 14ds has included information on the composition of patients over the working age treated in day hospitals by disease class. The distribution of elderly patients in day hospitals and the average duration of their treatment by disease class are presented. The following methods were used: statistical and analytical. Results. In the Russian Federation, between 2016 and 2025, an increase was observed in the proportion of patients over working age treated in day hospitals of medical organizations providing inpatient and outpatient care, along with a decrease in the average length of their stay. In 2025, the main reasons for treating elderly patients in day hospitals of medical organizations providing inpatient care were neoplasms, diseases of the eye and adnexa, diseases of the circulatory system, in day hospitals of medical organizations providing outpatient care, including home care, the main reasons were diseases of the circulatory system, neoplasms, diseases of the musculoskeletal system and connective tissue. Conclusion. The study showed that in the process of aging the population, the provision of medical care in day hospitals makes it possible to increase the availability of medical care to people older than working age.