The records of nine patients with double-chambered right ventricle, ventricular septal defect and subaortic narrowing were reviewed to clarify the natural history of the components of this pathological combination. All nine patients presented with heart failure related to a perimembranous ventricular septal defect, which underwent spontaneous reduction in eight and closed in one. Echocardiographic diagnoses of double-chambered right ventricle and subaortic narrowing were delayed in eight of the nine cases. The ratio of the distances from the pulmonary valve to moderator band/tricuspid valve annulus (the displacement index) was less than one in all patients. Subaortic narrowing was always discrete and was present at the diagnosis of double-chambered right ventricle. The subaortic narrowing was always recognized echocardiographically, and was seen in eight of nine patients at angiography. The subaortic gradient was 0–20 mm Hg and the subpulmonary gradient 0–110 mm Hg at catheterization. Five patients demonstrated aortic regurgitation. Subaortic narrowing should be diligently sought among patients with double-chambered right ventricle, and vice versa, even in the absence of a ventricular septal defect which may have closed. Both the subaortic narrowing and subpulmonary obstruction may progress, but probably at different rates. Patients with a perimembranous ventricular septal defect, particularly with a displacement index of less than one, should be monitored carefully for evolving subpulmonary obstruction, subaortic narrowing and aortic regurgitation. The subpulmonary obstruction should be resected at the time of any other surgical intervention. The indications for resection of the subaortic narrowing remain ill-defined.