Low birth weight (LBW) is one of the main causes of mortality in children less than one year old especially neonates. This research is for investigation of low birth weight rate and identify risk factors such as maternal age, way of delivery and number of pregnancies. Study was designed as a case-control. Of 3073 neonates at birth in 2005, 183 neonates had LBW. Of these 130 LBW were chosen as case group and 260 normal weight neonates (birth weight more than 2500 grams) were chosen as control group. Incidence of LBW in this study was 5.9 percent. In case group, there were 56.2% male and 43.8% female and in control group 56.9% male and 43.1% female. Sex of neonates with weight at birth didn't have significant relationship (p=0.8). In case group, 50.8% were born of normal vaginal delivery and 49.2% by caesarean section. In control group, results were: 62.3% normal vaginal delivery and 37.7% cesarean section. There was insignificant relationship between way of delivery and weight of birth. (p=0.8). In case group, 1.6 times increased incidence of caesarean section was seen (OR = 1.6). The greatest cause of cesarean in case group was multiple pregnancy (47.5%) and in control group was previous cesarean (33.6%). In 83.1% of case group, and 98.1% of control case group fetal presentation was cephalic, and 16.9% of case group and 1.9% of control group fetal presentation were noncephalic. There was significant relationship between fetal presentation and weight of birth (P=0.000). In case group, 10.3 times increase in non-cephalic presentation was seen (OR = 10.3). 73.8% of case group were pre-term and 26.3% were small for gestational age and term. Gestational age less than 37 week increased probability of LBW by 46.1 times (OR =46.1). Mean weight in case group was 1900 ± 611 grams and in control group was 3317 ± 472 grams. In case group, 5% of neonates were extremely low birth weight (ELBW), 16% very low birth weight (VLBW) and 79% were moderately low birth weight.