We have performed a research to establish the normal values of the plasmatic testosterone among 111 pupils, of both sexes, from 7 to 16 years attending our provincial schools. As we expected, the greatest increase of the plasmatic testosterone, in comparison with the previous ages, has been found in the group of the 13 years old females of the same age is more restrained, even if it's significative. By this way we could know the physiological values of the plasmatic testosterone in the children and adolescents of our population.