Abstract: An investigation on 11 indices for sport capabilities was carried out in 437 twin pairs of primary and middle school pupils in 1982 and 1983 in three districts of Shenyaag city, Liaoniag Province.The results showed that the difference is indicies was small and more concentrated between monozygotic twins while in dizygotic ones it was large and more scattered.All the indicies were related to heredity and three situations were revealed according to the calculated magnitude of heredity coefficient:Hereditary factor influenced strong1y on morphological indices of the body builds moderately on dash and spring abilities， and weakly on phy- siological functions, pliability and toughness.