This study was conducted to evaluate the growth performances of the Mia chicken carrying polymorphisms of the INS and GH genes. A total of 1,100 newly hatched of Mia chickens with c-haracteristic morphological features, were se-lected f-rom the Mia population in Son Tay town, and raised for evaluation of growth performance at Hadinco Farm. At 8 weeks of age, blood samples were taken f-rom the wing veins of each individual and were identified the genotype by PCR-RFLP method.The results showed that the A3971G polymorphism of the INS gene had 3 genotypes AA, AG and GG with a frequency of 29%, 55% and 16%, respectively. The T3737C polymorphism had 2 genotypes CT (78%) and TT (22%); no CC genotype was found. The C423T polymorphism has 3 genotypes CC, CT and TT with frequencies of 21%, 45% and 34%, respectively. The polymorphism of G662A had 3 genotypes, in which genotypes AA and AG had frequencies of 51% and 40%, respectively. All of the above genotypes did not have a significant effect on the weight of Mia chickens, while those carrying GG genotype of the G662A had bodyweight higher by 10.4% in the general population. However, the number of Mia chickens carrying this genotype in the population was very low, accounting for only 9%.