This study was undertaken to clarify the natural course of ventricular septal defect, and to find an index that would help in prenatal counseling. Between January 2010 and December 2014, 18188 fetuses underwent echocardiographic examinations. Of these, 228 isolated ventricular septal defect cases were retrospectively reviewed. In this retrospective study, the incidence of isolated ventricular septal defect was 1.25% (228/18188). There were 146 patients who underwent echocardiography after delivery in order to confirm the natural course of patients with isolated ventricular septal defect. Of the 146 cases, 64 cases (43.84%) had the ventricular septal defect naturally closed in the fetal period. Of the 82 patients with ventricular septal defect at birth, 25 patients showed natural closure during follow-up. However, four patients (2.74%) required surgical treatment for ventricular septal defect. In case of perimembranous defects, natural closure is more frequent in the fetal period than in the postnatal period. Our results indicate that 60.96% (89/146) of isolated ventricular septal defects diagnosed during the fetal life are closed naturally. Perimembranous type defect, small defect (<2mm) and maternal age less than 35years are the good prognostic factors for the natural closure during fetal life. © 2017 John Wiley & Sons, Ltd.