Noncompaction of the left ventricular myocardium (NCLV) is an uncommon congenital cardiomyopathy with poor prognosis. We describe a case of NCLV that developed in a pregnant woman and her neonate. A nulliparous woman was referred at 24 weeks' gestation due to dyspnea and fetal hydrops. Maternal echocardiography demonstrated NCLV with characteristic findings of prominent and excessive ventricular trabeculations and deep intertrabecular recesses in the left ventricle. An M-mode echocardiography suggested depressed left ventricular systolic function. A fetal echocardiography at 24 weeks' gestation demonstrated cardiomegaly, but morphologic findings were not definitive for NCLV. An emergency cesarean section was performed due to maternal heart failure. A neonatal echocardiography diagnosed NCLV with depressed left ventricular systolic function. The neonate died of cardiac failure on the second day of life. Autopsy confirmed the echocardiographic findings. Since patients with NCLV may develop heart failure, multidisciplinary management is mandatory. In addition, awareness of familial occurrence of NCLV should be kept in mind for early diagnosis in the fetus and neonate.