Objective To investigate the differences between prenatal and postnatal ultrasound findings in isolated ventricular septal defects.Methods Totally 244 cases of isolated ventricular septal defect were retrospectively analyzed and followed in one year after birth.All fetus were divided into the correct group and the error group according to the postnatal results.The size and type of ventricular septal defect and ventricular shunt were assessed and analyzed statistically.Results In all of the 244 cases,correct group included 181 cases and error group included 63 cases.There was no significant difference in the type of defects between two groups (P=0.061);there were significant differences in the size of postpartum defect and the velocity of ventricular shunt between the two groups (both P＜0.05),and no significant difference of the direction of shunt between two groups (P=0.408);there were significant differences in the size of defects between the prenatal and postnatal in correct groups (P＜0.05),but the direction of shunt had no significant difference (P=0.087).Conclusion There is certain detection rate in prenatal diagnosis of isolated ventricular septal defect;anatomical characteristics of defect may affect antenatal examination results.There was significant difference between prenatal and postnatal ultrasound in the same lesion.