Abstract Background: Schistosomiasis is a complex acute and chronic parasitic infection by blood flukes and it is a neglected tropical parasitic disease. Schistosome infections are higher in children and adolescents due to high rate of contact behavior with cercaria-infested water bodies. The prevalence of intestinal parasitic infection in general and schistosomiasis in particular varies in person, time, and place. Moreover, intermediate host snail’s distribution, patterns of environmental contamination with human excreta and water contact by humans are some predisposing factors for schistosomiasis. Objectives: - The aim of this study was to determine the prevalence of Schistosoma mansoni infection and associated factors among primary school children in farming rice cultivating villages of Fogera district, Northwest Ethiopia. Methods: A school based cross sectional study was conducted in Fogera district from February to June 2018. A total of 422 primary school children were recruited using systematic random sampling technique. Demographic characteristics of the study participants and data on factors associated with S. mansoni infections were collected via a structured questionnaire through face-to-face interviewing. Stool specimens were collected from each study participant and processed via Kato-Katz technique for microscopic investigation. All the data were entered and analyzed using SPSS version 23 and descriptive statistics were used to describe study participants to relevant variables. Bi-viariate and multivariate regression were used to measure association of dependent and independent variables. Those variables with P<0.2 in the binary logistic regression were taken to multiple regression analysis and the AOR was calculated to control potential confounders. P-value less than 0.05 was taken statisticaly significant. Result: The overall prevalence of helminth infection was 35.1%. A total of five helminth species, namely: Schistosoma mansoni,(20.6%), Hookworm (8.3%), Ascaris lubricoides (4.5%), Hymenolepis nana (1%), and Enterobius vermicularis (0.7%) were identified. Higher proportion of Schistosoma mansoni infection was recorded among boys (13.2%) than girls (7.4%). In the bivariable analysis age (COR=2.00, 95% CI: 1.0-4.03; P=0.05), swimming in water bodies (COR=11.00, 95% CI: 1.48-81.30; P=0.02), higher frequency of swimming in water bodies (COR=4.12, 95% CI: 1.45-11.71; P=0.01) and crossing rivers barefooted (COR=5.14, 95%CI (1.56-16.89), P=0.01) showed statistically significant association with Schistosoma mansoni infection. However, only age (AOR= 2.24, 95%CI (1.05-4.78), p=0.03) and swimming (AOR=4.86, 95%CI (1.59-14.91), P=0.01) were found to be predictors of S. mansoni infection in the multivariate analysis. The intensity of majority of S. mansoni infections was light(51.7%). Conclusion and recommendation: The prevalence of S. mansoni was high in the study area. The age group 10-12 years and those who experience swimming were at higher odds of Schistosomiasis. Therefore, the school children need mass deworming and health education to avoid frequent swimming in the nearby water bodies. Key word:S. mansoni, Prevalence, School children, Fogera Distrit