Heat stress is one of the most important environmental pressures especially in tropics which reduce sexual performance by affecting whole vital system. Garlic () as an effective pharmaceutical plant has been proposed for increasing resistance against stress. Current research was carried out to study the effects of garlic hydroalcoholic extract on reproductive hormones in female mice under heat stress. Fifty female mice were studied in five groups and ten replications. Experimental treatments were control group (normal situation without receiving extract),0, 200, 400, and 800 mg/kg of body weight of extract for thirty days in term of 4 hours daily heat stress. Blood samples were taken at the end of experiment period and estrogen, progesterone, FSH and LH hormones were measured. Obtained data were analyzed using SPSS program. Heat stress reduced all sexual hormones significantly (p<0.05) in zero group but FSH and LH amount were increased by 400 and 800 mg/kg doses. Estrogen and progesterone amounts were increased significantly in 200, 400, and 800 mg/kg groups and were about control group. Considering the results, extract can be effective under heat stress and neutralize negative effects of stress by affecting pituitary - gonadal axis and ovarian secretion.