BACKGROUND: birth weight is one of the most serious challenges in maternal and child health in both developed and developing countries. It is considered as sensitive index of nation’s health and development. I aimed to assess the magnitude of low birth weight and its associated factors among women who gave birth at three government hospitals in Bahir Dar, Amhara, Ethiopia. METHODS: Facility based cross sectional study was conducted on 243 women who gave birth at three government hospitals in Bahir Dar city from June to August 2020.Single population proportion was used to calculate the sample size. Data entry was completed on a template prepared in epidata version 3.1 and analyzed by statistical package for social science (SPSS) version 23.Descriptive statistics were performed to describe the characteristics of the study participants. Crude and adjusted odds ratio with 95% of confidence interval were used to identify the significance of association. A P value of <0.2 was used to determine the significance of association. RESULTS: In this study the overall prevalence of low birth weight was 30.5%. Pregnancy induced hypertension (AOR 4.17, 95%, CI 1.67, 10.44) and gestational age at the time of delivery (<37weeks) (AOR 23.94, 95%, CI 5.43, 105.45) were significantly associated with low birth weight. Determining the women’s urine protein during pregnancy (AOR 0.27, 95%, CI 0.13, 0.59) had preventive effect. CONCLUSION AND RECOMMENDATION: There was high prevalence of low birth weight in the study area. Effective prevention and treatment of pregnancy induced hypertension, and prevention of preterm birth could reduce low birth weight. KEYWORDS: Low birth weight; Magnitude; Associated factors; cross sectional study; Ethiopia