Relative Age Effects (RAE) is the effect of over-representation of relatively older athletes compared to their younger peers within the in the same age cohort. It is believed, that those born in earlier have been found to have a better physical and psychological advantage compared to the later-born individuals in their teens. This study is aimed to investigate the prevalence of RAE among the athletes who represented Malaysia at the 2017 SEA Games in Kuala Lumpur. The birth months of the athletes (men = 463, women = 362) were analysed according to the quarterly distribution: (Q1: January to March; Q2: April to June; Q3: July to Sept; Q4: Oct to Dec). The Chi-Square goodness of fit (χ²) test revealed that the effect of RAE was prevalent for male athletes in the first quarter as compared to the fourth (Q1: 33% vs Q4: 21%); nonetheless, it is worth to note that no RAE was found among the female athletes. It was demonstrated from the study that amongst the medal winners, the male athletes born in the first quartile (32%) were significantly more than the other quartiles. Similarly, the same results were found among the female medal winners but in the second quartile (35%). Therefore, it could be concluded from the study that the selection of Malaysian SEA Games athletes was influenced by the relative age effects.