The reproductive failure in farm animals is due to various factors. The high productive ability of sheep is dependent upon its reproductive efficiency. The sexual ability of a mature male is dependent upon the capacity of the testis to produce optimal number of viable sperms and the interstitial cells to produce adequate quantity of androgens to ensure good sex libido and maturation. The male passes through androgenic phases depending on the functional activity of the reproductive organs at various ages. The characterization of puberty with the associated changes in the reproductive organs is the available tool for selection of a male for breeding. Information on changes that occur in the postnatal development of testis is very valuable to determine the onset of puberty and maturity. A knowledge of the histological changes is also very essential to gain a comprehensive knowledge on the reproductive physiology and to form a baseline for the interpretation of various pathological conditions of the testis and it''s duct system. The present work details the postnatal histological development of the testis and its duct system from birth to sexual maturity.