Gamesmanship is built on the principle that winning is everything. School athletes are encouraged to bend the rules wherever possible to gain a competitive advantage over their opponents. Therefore, the objective of this study was to identify the main moral decision-making in sports on behaviours among school athletes. Meanwhile, for the second and third objective of this study was to determine the differences of moral decision–making in sports on behaviours among school athletes between genders and sports. The study involved 220 school athletes who completed the Attitudes to Moral Derived Decision Making in Youth Questionnaire (AMDYSQ), which contains 24 items measuring athletes' moral decision-making in sports. Descriptive analysis was used to identify the main moral decision-making in sports on behaviors among school athletes. For inferential analysis, Independent T-Test was used to test the differences in moral decision-making on behaviors among school athletes between genders. Meanwhile, One-Way ANOVA was used to identify the differences in moral decision-making on behaviors among school athletes between major sports. The result found that the main domain of moral decision-making among Tunku Mahkota Ismail Sports School (SSTMI) athletes is keeping winning in proportion. Next, the findings indicated that there was a significant difference between genders in terms of acceptance of cheating and keeping winning in proportion, while there was no significant difference in acceptance of gamesmanship. For third objective, the results showed that there was no significant differences in acceptance of cheating and gamesmanship. However, there was significant differences in keeping winning in proportion between types of sports. Overall, this study provides insights into the moral decision-making of SSTMI school athletes and highlights the importance of considering gender and major sports when examining these behaviors. Further research in this area could help to develop interventions to promote positive moral decision-making among young athletes.