The effect of different oligosaccharides ? alpha-galactoside preparations from Lupinus albus seeds differing in sucrose content, raffinose and fructooligosaccharides on the growth of chicken intestine microflora and the hatchability and weight of the treated embryos were studied. The assessment of biological activity of these oligosaccharides was done in ovo on the chicken embryo model. The eggs of experimental groups containing twelve days old embryos were injected into the air cell with 0.2 ml of Ringer water solution containing 0.1763; 0.8815 and 1.763 mg/egg of an oligosaccharide preparation, while the control group was injected with 0.2 ml of Ringer water solution only. All oligosaccharide preparations in higher doses had an influence on chicken hatchability and increased bifidobacteria in the colon of two day old chicken. The number of bifidobacteria depends significantly on the kind of oligosaccharide preparation used and its dose. For all experimental groups, the number of bifidobacteria was significantly higher in comparison to the control.