2 cases of severe pulmonary valvular stenosis in two young adults aged 21 and 29 years respectively are presented. Despite the degree of stenosis (4 mm jet), the right ventricular pressures did not exceed systemic pressures because of severe tricuspid regurgitation. This dominated the clinical and anatomical findings, causing aneurysmal dilatation of the right atrium and displacement of the tricuspid valve to the left. The diagnosis of Ebstein's anomaly was raised in one case but excluded by echocardiography and angiocardiography. In spite of the severity of the symptoms and peripheral clinical signs, surgery of the right ventricular outflow tract, tricuspid valvuloplasty and resection of part of the right atrium led to a complete and rapid cure, confirmed by catheterisation one month after operation.