The month of birth has important implications for the development of sports talents, especially for some sports and age groups. The aim of the study was to analyze the effect of relative age-RAE - in young triathletes. For this reason, during the period 2012-2016 the birth quartile of 160 young triathletes who participated in the Valencian Triathlon League was identified, categorizing those who took part in high performance programs on one side, and on the other those who achieved medals. Chi-square, Kruskal-Wallis, and proportion contrast tests were applied through SPSS (R) and Microsoft Excel (R). The results showed that triathletes born in the first quartile of the year predominate in triathlon high performance programs and win more medals than the rest, especially gold ones.