The cell suspension of photosynthetic bacteria was fed to hens, and its effects on the components in eggs were investigated. In the eggs from the bacteria-fed hens(PBS-fed eggs), it was observed that a considerable increase in the proportion of the yolk and a slight increase in the shell proportion occurred. With the increase of yolk weight, the total fat content was significantly increased, while the content of cholesterol was rather decreased. It was noted that there were clear increases in the contents of fat-soluble and water-soluble vitamins(E, K_1, B_1, B_2 and B_6)and accumulation of ubiquinone in the PSB-fed eggs. In these eggs, the total protein content in the white was almost unchanged, but lysozyme content tended to decrease.