The aim of this study was to measure the effect of chicken GnRH-I injection of roosters on egg fertility, hatching traits, and performance in layer breeder. Sixteen male and 160 female breeder chickens were divided into four experimental groups. Each group is consisting of 4 males and 40 females with four replications. Comprising a control group, a negative control group (received 200 µl phosphate-buffered saline, PBS), a low hormone group (received 200 µl PBS + 10 µg cGnRH-I) and a high hormone group (received 200 µl PBS + 50 µg cGnRH-I). Injection of 50 µg cGnRH significantly increased the fertility percentage of laid eggs over control, PBS and low hormone injected groups after period I. Injection of either 10 or 50 µg cGnRH significantly increased the relative fertility percentages of eggs following period IV. Injection of 50 µg cGnRH induced a significant increase in the hatchability of set eggs and the hatchability of fertile eggs after periods I and II. Further research is needed to measure the impact of cGnRH on fertility and hatching rates by injecting both male and female of same breed and age with the same doses.