Abstract: The present paper reported the results of studies on the size of Schistosoma japo nicum egg granulomas in susceptible and poorly susceptible,vaccinated and non vaccinated,hosts as observed in bovines.It was noted that in both cattle and buffaloes,the mean size of the granuloma was smaller in vaccinated than in the non vaccinated.The vaccinated bovines will accordingly not only be benefited by the reduction of the survival rate of the challenged schistosomula but also by decreasing the size of the egg granulomas.