The effects of educational environment factors and processes on the increasing incidence of certain functional disorders and chronic diseases, which can collectively be referred to as school-related diseases, is a relevant issue of childhood and adolescence hygiene. Seeking to prioritize preventive effort directions, this study aimed to analyze trends in overall and primary morbidity from these diseases among Russian children and adolescents from 2015 to 2024. The data collected for the descriptive analysis covered children (0–14 years old) and older adolescents (15–17 years old); they were officially reported by the Central Research Institute for Organization and Informatization of Healthcare. We assessed the dynamics of morbidity at the level of classes of diseases and certain disease entities, and calculated the disease chronization indices (DCIs). The data were systematized and analyzed in Microsoft Office Excel 2020. The study suggests criteria for classifying certain health disorders as school-related. We identified persistent morbidity trends (noticeable throughout the study period) for individual ICD-10 classes, and observed high DCI values for diseases of the eye, the musculoskeletal system, and mental disorders. These findings may be associated with increased psycho-emotional stress, educational and visual demands, and insufficient physical activity. The analysis of morbidity trends identified the following priority areas for preventive work: promoting physical activity among schoolchildren, reducing psycho-emotional stress associated with examinations in grades 9 and 11, teaching students how to arrange their educational and leisure activities, promoting healthy nutrition, and increasing sleep duration.