Not AvailableAn experiment was designed to assess the effect of in ovo and pre-starter amino acid supplementation on growth performance and immune response of broiler chicken. Two hundred and sixty Cobb broiler eggs of uniform size were set for incubation. The fertile eggs were divided into two groups; one group was administered with in ovo amino acid solution (lysine 22 mg, methionine 10 mg and threonine 16 mg per egg) into the amniotic cavity on day 18 of incubation and other group remained without administration. After hatching, the chicks from each of the two groups were further sub-divided into two groups (with or without post-hatch amino acid supplementation) resulting in four groups. The post-hatch supplemented groups were fed a diet supplemented with 25% higher level of amino acids (lysine 1.68 mg, methionine 0.63 mg and threonine 0.99 mg). Consequently, group I served as a control without in ovo and without post-hatch supplementation, group II was without in ovo and with post-hatch supplementation, group III was with in ovo and without post-hatch supplementation, and group IV was with in ovo and with posthatch supplementation. The results showed a decreased hatchability on in ovo administration of amino acids. Chick weight and egg weight did not vary significantly (P>0.05). The BW gain, feed intake and FCR during 0–3 weeks of age did not differ (P>0.05) among the treatment groups. On the other hand, in ovo administration of amino acids alone or in combination with post-hatch supplemented diet significantly (P0.05) in terms of in ovo, post-hatch supplementation or their interaction. The in ovo or post-hatch supplementation of amino acids diet did not influence (P>0.05) the weights of digestive organs except for significantly (P>0.05) higher breast meat weight in post-hatch supplemented diet. It is concluded that supplementation of lysine, methionine and threonine in ovo and in pre-starter diet is beneficial for growth and breast meat yield of broiler chicken.Not Availabl