The present study aimed to investigate the effect of a synthetic GnRH (Fertagy]®) injection during summer on steroid hormones levels and lipido-gram in male farm animals. Six healthy mature males farm animals (from “et of cattle, buffalo, sheep and goats) were di-ded into 2 “omparable equal groups. The first men . ‘ep 4S a control, while the second injected (im) with 250 and 100ug for large and Smal! animals, respectively. ‘samples were collected just before (0 time), then every An hour for six times after injection. plasma samples were assayed for testesterone , estradiol and cortisol levels. Also, concentration of total lipids, cholesterol and triglycerides were determined. results of the present investigation reported that GnRH injection induced marked increase in testesterone (for 3-4 hrs), decreas in estradiol ( except in buffloes) and little changes in cortisol level in male farm animals during summer. results of lipidogram revealed non significant changes, however, total lipids and triglycerides values tends to increase and cholesterol tends to be decreased with advanced of time following Gnrh injection in all studied males. MOREOVER,correlation coefficients were recorded among the studied parameter. it is concluded that treatment of male farm animals with GnRH during summer may increase sexual desire and fertility.