The relative lengths of the index finger to the ring finger (2D:4D) is sexually dimorphic. It is believed that the 2D:4D negatively correlates with prenatal testosterone and positively with prenatal estrogen. Low 2D:4D is related to masculine traits such as aggression, physical fitness and performance in different sports. The aim of this study is to investigate the relationship between the 2D:4D and physical fitness among 7 to 13 year-old boys. 316 boys were selected, all participants were in

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... e-pubertal stage. After completing the consent by their parents; height, weight, lengths of the index and ring fingers and physical fitness such as: strength, muscle endurance, power, speed, agility, flexibility and aerobic fitness were measured. The partial correlation coefficients was used to determine association between variables. Data analysis was done by SPSS software, version 20, and the level of significance was considered as P≤0.05. The results showed that the digit (2D:4D) ratio has no significant correlation with handgrip strength and aerobic fitness (P ˃0.05). Also, according to the results, no correlation has been observed between the 2D:4D and muscle endurance, power, speed, agility and flexibility (P ˃ 0.05). It seems that 2D:4D is associated with level of testosterone and prenatal estrogen; this index has no significant correlation with physical fitness in children and cannot be used to identify and discover talented individuals for various sporting fields. However, more researches are still needed in this area.