Introduction Low birth weight (LBW) is a high risk for children's health and a problem of public health in under developing countries. SGA increases neonatal and infant death, and neonatal and adult morbidity. So the present study aimed to assess the incidence of LBW, SGA and their related factors in Sabzevar in 2011 to 2012. Materials and Methods This prospective descriptive-analytic study was conducted on 481 low birth weight neonates born in Mobini academic hospital of Sabzevar in 2011. Neonates who their BW was Results 480 (6.33%) of participating newborns were LBW (out of 7599). Mean weight of LBW neonates was 2039.1±9.6 g. Among LBW neonates, 62 (12.7%) and 24 (5%) of neonates were VLBW and ELBW, respectively. 162 (34.1%) of neonates were SGA (out of LBW neonates). SGA rate was 2.2% (out of total newborns). Family income (p-value=0.026) and mother's education (p-value=0.004) were significantly lower in SGA neonates rather than LBW neonates. The incidence of mothers' urinary infection in VLBW neonates was significantly higher than non-VLBW neonates (p-valu