A study to the determination of schistomiasis mansoni transmission rate was done in the city of Riachuelo, state of Sergipe, in wich the prevalence in stool examination was determined in advance, as 50,54%. As transmission rate, it was considered, the percentual of children between 0 and 10 years old, with negative examinations (stool or intradermoreaction) who, after a year exposition to the focus, turn it positive. The city was divided in two different areas, such as: area I - economic and area II - sanitary, and the transmission rate has been estimated through stool examination and intradermoreaction. It was observed that the area I, with better economics and sanitary conditions presented a smaller transmission rate, such in stool examination (11,62%), as in intradermoreaction (13,46%), when compared to area II (12,39% and 17,59%). The authors condude that the transmission rate comes from the intensity contact between the children and the infectious focus, which reflects the comunity level of hygiene and sanitary education. They consider, too, public Health proceedings aimed to schistomiasis struggle, can be estimated through the determination of rate oscilation.