Soil-transmitted helminthic infections are among the most common infections worldwide and affect the poorest and most deprived communities. School age children between ages of 5 to 15 in most developing countries are at greatest risk of chronic helminth parasitic infection and helminth-associated morbidities. This study was aimed to determine the prevalence of soil transmitted helminth parasitic infections and associated risk factors among three government elementary schools children, Bahir Dar, Ethiopia. A school based cross-sectional study was conducted from November-February 2019/2020 involving a total of 316 study participants. A systematic random sampling method was utilized to select the study participants from the study schools. Data related to socio-demographic characteristics of the study participants and risk factors for STH infections were collected using a pretested questionnaire survey. Parasitological examinations of stool samples were done using Formol-ether concentration methods. Study participants whose age ranged from 5 to 15 years were enrolled in this study. The overall prevalence of STH infection was 21.5% (68/316). The predominant STH parasite species was Ascaris lumbricoides with prevalence of (11.4%) followed by hookworm infection with prevalence of (7.3%), Trichuris trichiura (1.9%) and Strongloides stercoralis (0.9%). Age group 10-15 with AOR 3.109 (95% CI: 1.033, 9.350), residence in kebele 16 with the AOR 2.990 (95% CI: 1.082, 8.264), respondents who came from illiterate mothers with AOR 4.689 (95% CI: 1.410, 15.59) and family size 4-6 with AOR 3.286 (95% CI: 1.299, 8.313) were significantly associated with STH infections. However, factors such as, sex of students, latrine usage, family income level, walking with bare foot, hand washing before meal were not significantly associated with STH infections. The prevalence of STH infection is still an important health issue in the study participants even after the implementation of school deworming programs. In the study, age, residence, mother education level and family size were identified as risk factors that significantly associated with STH infections. Keywords: Bahir Dar, Ethiopia, Prevalence, Risk factors, School age children, Soil-transmitted helminthic infections