Isolated ventricular noncompaction of myocardium is a rare congenital disease due to an arrest of myocardial morphogenesis during foetal development. It is characterized by a thin compacted epicardial and an extremely thickened endocardial layer with prominent trabeculations and deep intertrabecular recesses. The persistence of myocardial noncompaction is usually an associated anomaly in patients with congenital left or right ventricular outflow tract obstruction. However, isolated noncompaction of myocardium is not associated with any factors that would explain it apart from the foetal arrest of compaction of the ventricular myocardium. The disease results in systolic and diastolic ventricular dysfunction, systemic embolism and ventricular arrhythmias. We describe a case of isolated noncompaction of the ventricular myocardium in a 20-year-old man who presented initially with ventricular tachycardia.