Objective and Background: The incidence of prenatal mortality is one of the most important health indicators of a community. Through identifying factors which bring about prenatal mortality and through raising awareness of pregnant mothers concerning attention to medical cares over pregnancy period, such prenatal mortalities can be remarkably reduced. The main objective of this study was to determine the frequency of prenatal mortality rates and its causes over one- year -period in Abhar Emdadi Hospital. Materials and Methods: This cross sectional study was carried out on 55 fetus and neonatal mortality cases from week 22 of pregnancy to day 28 after birth. They died at birth or after birth. The collected data was analyzed using SPSS version 16. Results: The common causes of prenatal mortality were prematurity and respiratory distress syndrome and then IUFD (Intra Uterine Fetal Death) and chromosomal abnormality. 21.8% of prenatal mortality cases was due to IUFD.78.2% of prenatal mortalities happened after birth. 88% of prenatal mortality occurred in premature neonates. Common causes of IUFD were congenital abnormality and preterm birth in comparison with neonates who born alive and whose deaths were mostly due to severe prematurity, RDS (Respiratory Distress Syndrome), and chromosomal abnormality. Conclusion: The leading factors to prevent prenatal death rest on inhibiting preterm birth and low birth weight delivery. Also emphasis on special cares during prenatal period, identifying and following high risk mothers and setting up NICU wards could vastly reduce prenatal mortality rates.