Introduction: Low birth weight is defined as birth weight less than 2,500 grams. More than 20rnmillion infants are born each year weighing less than 2500 gm, accounting for 17% of all birthsrnin the developing world. Similarly, according to Ethiopian demographic and health surveyrn(EDHS 2011), 11% weighed less than 2500 gm. Birth weight plays an important role in infantrnmortality and morbidity, development, and future health of the child. Weight at birth is directlyrninfluenced by general level of health status of the mother.rnObjectives: The main objective of the study is to identify determinants of low birth weight inrnDebre Berehan Referral hospital.rnMethodology: The study was a facility based unmatched case-control study design conducted byrnreviewing cards of mothers and neonates who delivered in Debre Berehan Referral hospital justrnthree years back from study period (February to June 2015). Data analysis was done by SPSSrnversion 20 and bivariate and multivariate statistical methods were used.rnRESULT: In this study 441 mothers and newborns cards were included yielding 100 % responsernrate. From this 147 mothers and newborn cards were selected for case group and 294 mothers andrnnewborn cards were selected for control group .The mean birth weight was 2077.55gmrn(S.DÂ±325.78 gm) for the neonates with low birth weight and 3230.0 (S.DÂ±449.73 gm) for thernneonates with normal birth weight. Out of 441 mothers in both case and control groups, most ofrnthem were between the age group of 21-25 years, which is 39.5% and 36.1% for case group andrncontrol group, respectively. Those newborns with gestational age less than 37 weeks were 4rntimes (AOR=4, 95%CI (1.61,8.13) p-value =0.0001) more likely to be delivered low birthrnweight than those new born greater than or equal to 37 weeks of gestation. So, significantrnassociation is found between gestational age and BW. Pregnancy induced hypertension (AORrn=3.415, 95% CI (0.855, 13.645 p-value 0.047) have significant association. Another variable thatrnhave significant association with BW is hemoglobin level (AOR 1.0, 95% CI (1.0, 1.0) p-valuern=0.045).rnConclusion: According to the findings of this study the determinant factors for LBW are:rnGestational age less than 37 weeks, hemoglobin level of the blood, PIH. So that interventions tornprevent pre term, control blood hemoglobin level of the mothers, prevent anemia and preventrnhypertension are important to manage LBW.rnKey words: low birth weight, maternal factors, case control, Debre Berehan.