Abstract: The cellular responses against different developmental stages of Schistosoma japonicum. in the liver of C57BL/6 mice are reported. In hepatic sinusoids and tissues around interlobular veins, eosinophils and lymphocytes begin to increase on the 7th day post infection (PI), while plasma cells appear around interlobular veins on the 28th day PI. These findings suggest that the responses of the mice against the schistosomulum-adult worm of Schistosoma japonicum are immune reactions. As egg-maturation proceeds, there is a concomitant rise in the number of eosinophils in sinusoids and various immune cells in tissues around interlobular veins. The host responses against both schistosomulum-adult worm and the egg consist of a series of consecutive steps, the response versus different developmental stages having its own characteristics. It is interesting to note that once the egg develops to maturity, strong cellular responses around the eggs appear instantly with the rapid formation of granulomas. Hence the immune response to schistosomulum-adult worm before the maturity of the egg might play a role in the formation of egg granuloma. This is certainly a subject worthwhile to study.