Introduction: Raising awareness of women on danger signs of pregnancy is crucial for safe motherhood. In Ethiopia, a country where maternal morbidity and mortality is high; little is known about the knowledge level of pregnant women on obstetric danger signs and its associated factors. Objective: This study aimed to assess pregnant women’s knowledge about obstetric danger signs and associated factors in Ethiopia. Methods: A community based cross-sectional study was conducted from April 1 to October 30, 2013, on a sample of 802 pregnant women systematically selected from 8 rural and 2 urban Kebeles (the smallest administrative unit). A pre-tested structured questionnaire was used to collect the data. The collected data were entered into a computer by using Epi Info version 3.5.3 and analyzed using SPSS version 20 for windows. Binary and multiple logistic regressions were done to explore factors determining maternal knowledge on obstetric danger signs. Results: Seven hundred sixty nine women participated in the study making a response rate of 92.2%. Out of 769 women participated in this study, 56.8% were knowledgeable about obstetric danger signs. Place of birth (AOR=0.53, 95% CI=0.32-0.88), Women’s educational status (AOR=6.98; 95%CI=3.73-13.08), high Parity (AOR=2.87; 95%CI=1.53-5.39) and Lack of antenatal care (AOR 3.46; 95%CI=1.54-7.79) were found to be significantly associated with knowledge on danger signs during pregnancy, labour and post-partum. Conclusion: This study showed low level of Knowledge of danger signs during pregnancy among women in Debaytilatgin district. The promotion of universal antenatal care follow-up, educating women, avoiding high parity and advocating institutional delivery is very important.