Distributions of eggs of the four main geographic strains of Schistosoma japonicum in the viscera of infected hamsters and mice were studied. The results of the study show that the percentage distributions of eggs of this parasite in the visceral organs of its host were influenced by the strain of the parasite, the species of the host, and the intensity of infection in the host. It may be stated that in general, with the C and F strains, the percentage distributions of eggs in the visceral organs of hosts were higher in the liver than in the small intestine; with the J and P strains, higher in the small intestine than in the liver except in mice infected with one male and one female cercariae of the P strain, where the mean of the percentages of eggs in the liver was higher. As to the species of host, the mean percentage of eggs in the small intestine was lower in the hamster than that in the mouse, and vice versa in the large intestine. When the intensity of infection in the host was at the lowest level, the percentages of eggs were mostly higher in the liver and large intestine, and lower in the small intestine, than in the corresponding organs of the host with the high intensity of infection.