Rice field rat (Rattus argentiventer) has been widely known as pest of rice and crops. This rat is also the definitive host of Schistosoma incognitum. The purpose of this study is to know the proportion of rats infection with this parasite in those two ares. Previous study of Hadidjaja and Lukman (1983) showed the prevalence of 43 percent in Cakung area and this area was endemic for this parasi…