Isolated noncompaction of the ventricular myocardium (INVM) is an uncommon cardiomyopathy which results from an intrauterine arrest of normal compaction of the loose interwoven meshwork of the ventricular myocardium. This congenital cardiomyopathy is characterized by the persistence of fetal myocardium with prominent trabecular meshwork and deep intertrabecular recesses, often associated with systolic dysfunction and ventricular dilatation. Familial occurrence has been reported with a less severe form of abnormalities. We report a case of INVM in a family in which three of members were affected by this disorder. A 2-year-old female was referred to our hospital with a diagnosis of dilated cardiomyopathy (DCMP). She had taken an anticongestive therapy (using digoxin, diuretics) due to DCMP since 2weeks after birth. Her echocardiographic finding revealed severe dysfunction of the left ventricle with prominent trabecular meshwork and deep intertrabecular recesses. Endocardial biopsy showed hypertrophic myocyte but nonspecific finding. Echocardiographic screening in her first-degree relatives demonstrated INVM in her father and a sister who were asymptomatic.