This study aimed to investigate the effect of in-ovo injection with probiotic on hatchability traits, growth and physiological response of post-hatch Sinai chicks.Both body weight gain and feed conversion ratio were significantly improved as a result of in-ovo injection with 1.0 g probiotic/L than the negative control during the overall experimental period after hatch (0-12wks of age). Relative weights of some giblets and organs were increased as a result of in-ovo injection with probiotic as compared with negative control with or without significant effect.in-ovo injection by probiotic with 1.0 or 2.0 g / liter at 18th day of incubation period could be used to improve hatching and subsequent growth performance of hatched Sinai chickens.