Biometrical as well as quantitative histological studies were carried out on the seminiferous tubules of the testis of Fayoumi and Rhode Island Red cockerels from one day to 24 weeks of age. Various morphological parameters such as the diameter and the absolute volume density of the seminiferous tubules, the total number of germ cells, the first appearance of spermatids and sperm and the nuclear cross sectional area of the Sertoli cells were applied on the testes of both breeds and documented that Fayoumi cockerels reached sexual maturity earlier than those of the Rhode Island one.