The development of the right gonad tissues from an inbred line 2-month-old ovariectomized female chick of GSP inbred line transplanted under the back skin and inside the abdomen of castrated pre-pubertal GSP male chicks were elucidated in this study. After 10 months, the host males were killed and the gonad grafts were subjected into histological and genetic analysis. Secondary sex characteristics observed in the male hosts were identical to the normal males based on increased in head furnishings, spur development and male plumage pattern. Around 10% of the total grafts collected inside the abdominal cavity had 50-60% increase in volume, whereas no gonad grafts developed under the skin. Histological analysis of the gonad grafts showed a more advance differentiation into testicular tissues and active mitotic division of germ cells compared to intact gonad that developed in the ovariectomized chicken. The seminiferous tubules contained spermatocytes as the most advanced germ cells and the size of the lumen observed in the gonad grafts were mostly normal with some dilation. FISH analysis revealed numerous spermatids with fluorescent signals bearing the W chromosome indicating that the second meiosis occurred normally, although more advance germ cells were not observed. These results demonstrate that the right gonad obtained from a female sex reversed chicken maintains its testicular tendency and capable of maintaining the structural integrity as well as physiological characters of a male testis when transplanted to a castrated chicks.