The objective of this study was to compare the expression of pituitary gonadotropin genes between three populations of native birds in Iran and Hyline W-36. One hundred and twenty-eight 37-week-old chickens (Golpayegan, Marandi, Isfahan, and Hyline W-36) were studied for 12 weeks. All birds were reared in the same cage system and under similar nutritional and managerial conditions. Quantitative characteristics such as egg number, egg weight, egg production percentage, egg mass, feed intake, and feed conversion ratio were calculated. At the end of the trial, five hens in each group were slaughtered after weighing, and their heads, livers, ovaries, and oviducts were removed. The gene expression of LH and FSH was determined by reverse transcription-polymerase chain reaction (RT-PCR), after RNA extraction from the pituitary gland. The results showed that Hyline W-36 had the highest egg number, egg weight, percentage of egg production, and egg mass. The feed conversion ratio was the highest in the Marandi, but the lowest was observed in the Hyline W-36. Expression of the FSH gene in Hyline W-36 was higher than in other groups. A positive and significant correlation was observed between the expression of the pituitary gland FSH gene, egg mass, and relative ovarian weight. The difference in production performance of various genetic populations seems to be mainly due to the differential expression of the FSH gene in the pituitary gland. Therefore, for genetic enhancement programs in native chicken, these results may help identify the metabolic pathways of gonadotropins gene expression, their effects on the ovaries, and reproductive activity. پرونده مقاله