Selection is the basic tool to exploit and improve the productive potential of livestock. The objectives of the present study were to evaluate the effect of selecting Japanese quail at 4-week for high body weight for four successive generations on the growth traits including body weight (BW) and average daily gain (ADG) and on the expression level of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), adenine nucleotide translocase (ANT), uncoupling protein (UCP) and Cytochrome C Oxidase subunit III (COX III) genes. Growth traits were evaluated for the base, 1^st, 2^nd, 3^rd, and 4^th generations. Total RNA was extracted from the liver then cDNA was synthesized. Real-time polymerase chain reactions were performed using the SYBR Green PCR Master Mix. The 4^th generation of this study recorded the highest and significant values for body weight at zero (hatching), 2^nd, 4^th and 6^th week of age (BW0 = 9.75, BW2 = 75.16, BW4 = 163.46 and BW6 = 253.13 gm, respectively), and for average daily gain (ADG0-2 = 4.67, ADG2-4 = 6.36 and ADG0-6 = 5.79 gm, respectively). Moreover, the 4^th generation recorded the highest and significant mRNA expression of GHR and IGF-1 genes in the liver (1.80 and 1.66 fold change, respectively). In contrast, the base generation showed the highest and significant levels of hepatic mRNA expression of ANT, UCP, COX III genes (1.08, 1.24 and 1.05 fold change, respectively). We may conclude that these genes are promising candidate biomarkers for improving growth traits, leading to increased quail marketable meat.