The purpose of the study: To study the features of the quality of life of first-graders, taking into account gender differences and cognitive abilities. Design: An open prospective non-randomized comparative clinical trial. Materials and methods: 631 children were examined, students of the first grades of secondary schools without a specialized bias № 110, 83, 75, 67, 9 Rostov-on-Don using the international questionnaire PedsQL 4.0 – Pediatric Quality of Life Inventory. To assess the cognitive development of children, the D. Wexler scale was used with the determination of the intellectual coefficient. Results: First-graders with a high level of cognitive development have reduced indicators of physical and emotional functioning, as well as the overall quality of life score. Girls with a high intellectual coefficient, in comparison with boys, have lower physical, emotional, school functioning and higher indicators of social functioning. The indicators of quality of life in children with a high level of cognitive development do not reflect the same in children who do "excellent". Conclusion: The revealed features of the quality of life of first-graders with different levels of cognitive development require differentiated medical, psychological and pedagogical support of children in this age period and further study of their health.