The double-chamber right ventricle is a congenital cardiac malformation usually associated with other cardiac defects, seldom isolated and in adult subject. It is characterized by the presence of an anomalous bundle that divides the right ventricle into two chambers. The clinical and electrocardiographic signs of isolated double-chamber right ventricle are few and not specific. An echocardiographic diagnosis of isolated double-chamber right ventricle is reported. In a 18-year-old asymptomatic male with systolic murmur 2/6 at third space over the left sternal border, right ventricular hypertrophy and intraventricular conduction delay at ECG, two-dimensional echo showed an anomalous transversal muscle bundle that divided the right ventricle into two chambers, superior and inferior. Color Doppler showed a diastolic tricuspidal-like flow through a paraseptal discontinuity of the bundle and a systolic jet that reached the right atrium, with a pressure gradient of 30.9 mmHg. The absence of symptoms and other cardiopathy, without significant right outflow tract obstruction, was considered as an index of a good prognosis; therefore cardiac catheterization was not advised.