One of the most important health indices in different societies is the birth weight of neonates which is affected by several factors. It is essential to be aware of these factors for further care of both mother and her fetus during pregnancy. The association between birth weight of neonates and some influential factors on them were examined in this study. In this cross sectional research, 245 neonates of Shoushtar County were studied in 2013. The data were collected from medical files and by interviewing with mothers. The neonate and mother characteristics, pregnancy and delivery statues were determined. Data were analyzed by SPSS 16 software, Chi square and T tests, analysis of variance, ROC curve and multiple regression. Mean (±SD) of the examined babies’ weight was 3258(±436) grams. Gestational age(P<0.001), gender(P=0.04), rank of birth(P=0.012) and period between two pregnancies(P=0.028) had a significant relationship with birth weight. Regression model also included gestational age, rank of birth, type of delivery and gender(R²=0.242). and gestational age variable had a higher sensitivity(0.85) and specificity(0.91) by ROC curve. In this study, gestational age, rank of birth, period between two pregnancies and gender had a meaningful relation with birth weight and regression model could illustrate and anticipate 24% of changes in dependent variables. Prevention of preterm delivery and preparing of exclusive cares for mothers with low duration between two pregnancies and in primiparous can increase probability of infants born with normal weight.