Relevance. To reduce differences in the age structure of the population when comparing the epidemic situation for infectious and non-infectious diseases, it is advisable to carry out a standardization procedure for existing age groups. Aim: to justify and propose a methodology for standardizing morbidity according to the Federal Statistical Observation Form of Rosstat No. 12 “Information on the number of diseases registered in patients living in the service area of a medical organization.” Materials. We analyzed the structure of Rosstat form No. 12 by age groups of patients included in it. The WHO global population standard was used. Results. The structure of the form distinguishes four age groups: 0–14 years, 15–17 years, working age and over working age; at the same time, the border between adults of working age and older than working age from 2020 to 2028. is changing. The share of people of different ages in the world standard population is: for children 0–14 years old 0.261422, 15–17 years old 0.050805. The share of people of working age increases from 0.545566 (before 2020) to 0.628242 (in 2028). The share of people over working age decreases from 0.142207 (before 2020) to 0.059532 (in 2028). Coefficients for the Scandinavian and new European population standards are also calculated. The sequence of actions for carrying out the standardization procedure is given, which includes the following stages: 1) calculation of the age structure of the population; 2) calculation of the correction coefficients for each age group; 3) calculation of age-specific and standardized morbidity for each age group; 4) calculation of the standardized number of cases; 5) calculation of standardized morbidity. An example of standardization of the incidence of cerebrovascular diseases is given. Conclusion. The presented methodology for standardizing morbidity indicators, based on the data available in form No. 12, is recommended for use in analyzing time series, especially in conditions of changing population sizes.