Aim: To investigate the influence of strength training on the physical development and physical fitness of 16-17-year-old young men. Materials and Methods: The research, which was conducted in 2024-2025, involved 117 high schoolers of 10-11 grades (16-17-year-old young men). Two groups of young men were formed: the experimental (EG, n = 56) and the control (CG, n = 59): the CG young men were engaged in a generally accepted program; the EG young men were engaged in strength training. Research methods: bibliosemantic, medical and biological methods, testing, methods of mathematical statistics. Results: The positive influence of strength training on the physical development and physical fitness of 16-17-year-old young men was revealed. The EG young men showed significant (p < 0.05-0.001) improvement of such indices as Pignet (by 3.6 c. u.), Brugsch (by 18.9 c. u.), strength (2.5 c. u.), Erisman (by 0.8 c. u.), body weight (by 1.4 kg/m2), as well as results in pull-ups (by 4.5 times), in push-ups (by 7.3 times), in a standing long jump (by 6.6 cm), in sit-ups (by 9.3 times). In the CG, there were no significant changes in all tests (p > 0.05). At the end of the research, most of the EG indicators were significantly better compared to the CG. Conclusions: The introduction of strength training in the physical education of senior high schoolers is one of the important factors for improving their health, harmonious physical development, and increasing physical fitnes