Background: Soil transmitted helminthes (STHs) and intestinal Schistosomiasis are amongrnthe most common cause of human infections and neglected tropical diseases which arerndistributed throughout the world and cause thousands of avoidable outpatient morbidity andrnmortality, especially in school-age children. They are also the leading cause of gastrointestinalrnpain, malnutrition, malabsorption, anemia, mental retardation and other diseases. Thernprevalence and associated risk factors among primary school children was lacking in the studyrnarea.rnObjective: The aim of this study was therefore to determine the prevalence of soilrntransmitted helminthiasis and intestinal schistosomiasis and associated risk factors amongrnprimary school children in Guder and Ambo town.rnMaterials and Methods: Institution based cross-sectional study was carried out from Aprilrn2018 to May 2018 among primary school children in Guder and Ambo town. A total of 320rnprimary school students were selected by simple random sampling technique. The prevalencernof STH and intestinal Schistosomiasis was determined by formol-ether concentrationrntechnique. Assessment of Socio demographic characteristics of students and associated riskrnfactors was also conducted by well-developed questionnaire. Data analysis was done by usingrnthe SPSS version 16 software.rnResult: Out of 320 study subjects 57 students (18%) had one or more soil transmittedrnhelminthes and 15 students (4.68%) had Schistosoma mansoni infection. From soil transmittedrnhelminths, A.lumbricoides was the predominant isolate (13%) followed by T. trichiura (3.7%)rnand hookworms (2.2%).rnConclusion: In this study large Family size, not nail trimming and unavailability of improvedrnlatrine were identified as predisposing factor for soil transmitted helminthes infections. Allrnschool children enrolled and not enrolled in this study should be treated according to WHOrnguideline to control the transmission of these parasitic diseases. Access to improved latrinerncould also help for reduction of soil transmitted helminthes and intestinal schistosomiasisrnprevalence below the percentage found in this study