The objective of this study was to investigate the effects of a 12-week basic tennis training program on the personality development of early adolescents aged between 9 and 11 years. The research methodology consisted of a single group pre-test/post-test design implemented with a total of eight volunteer children (three boys and five girls). The Personality Inventory (PERI), a data collection tool used to quantify (openness to experience, sense of responsibility, extraversion, compatibility, emotional balance). The mean calculation for each personality trait is provided in the form of descriptive statistics while the Wilcoxon test was used to identify differences between the pre- and post-tests. In conclusion, the research team observes that by improving early adolescents' openness to new experiences, tennis training facilitates the development of related characteristics, such as individuality, well-roundedness, ability to generate new ideas, creativity, flexibility, optimism, even temperament, low anxiety, attention to detail, discipline and ability to plan.