Introduction. According to special studies, the proportion of the population with some form of disability is 16% of the total global population, and as a result, the increase in disability is accompanied by a decrease in the health potential of the population. The analysis of the dynamics forming disability tendencies provides an opportunity to forecast the trend of disability of the population, taking into account its negative tendencies and the levels of its formation. Purpose of the investigation. Analysis of the dynamics of primary disability in the population, identification of trends, assessment of tendencies and forecast. Materials and methods. A retrospective observation of the dynamics of primary disability of the population aged 18 years and older in the Russian Federation and Moscow for 2016-2023 was carried out. Methods of observation, comparison, analytical quantization, special methods for assessing tendencies and trend reliability, methods for constructing point and interval forecast models, estimating forecast accuracy and credible interval for point forecast models are applied. Results and discussion. There was an increase in the number of people recognized as disabled for the first time in 2023, compared with 2016, in the Russian Federation (Kr=1,09; base growth rate +9,01%) with an uncertain tendency (R2=0,475), and a decrease in the indicator for Moscow (Kr=0,84; the base growth rate is -16,31%) with a pronounced sustained tendency (R2=0,8015). According to the interval forecast, in 2028, the number of individuals recognized as disabled for the first time in the Russian Federation and Moscow will be within the boundaries of 865,06;1458,72 '000 People and 24552,36;44996,14 persons with a 95% probability, respectively, showing an increase for both comparison territories. An uncertain tendency (R2=0,4581) has been established towards an increase (Кr=1,099) in the primary disability coefficient of the population of the Russian Federation (base growth rate of 9,86%) and a pronounced sustained tendency with a negative trend in the dynamics of the indicator for the population of Moscow (Кr=0,79; R2=0,8463) with a high rate of decline (the base growth rate is -21,29%). Prognostic point models for 2028 show an increase in the rates of primary disability of the population for both comparison territories (98,65 and 25,68 per 10,000 population, respectively, for the Russian Federation and Moscow). The values of the increase rates indicate an increasing trend and acceleration of the process of formation of primary disability in the population of the Russian Federation, and a decreasing trend and slowing of the process of formation of primary disability for the population of Moscow. Differences in the rate of change of dynamic processes have been established: with each time period, the level of primary disability in the population of Moscow decreased by 3,4%, and the level of primary disability in the population of the Russian Federation showed an increase of 1,4%. Conclusion. Tendencies in the primary disability of the population of a megalopolis, compared with the Russian Federation, are characterized by: differences in the dynamics of the number of individuals recognized as disabled for the first time; differences in the levels of primary disability of the population; differences in the intensity and direction of dynamic processes; differences in the rate of change. The results of the interval forecast of the number of individuals recognized as disabled for the first time and the point forecast of the level of primary disability with a lead period of five years show an increase in indicators for both comparison territories with high accuracy of predictive models.