We report here two cases of patients admitted in our institution for heart failure. The first had been previously diagnosed with severe aortic valve stenosis and was referred for aortic valve replacement. The myocardial and valvular anatomy combined with the Doppler profiles allowed, however, to suggest the diagnosis of a discrete subaortic membrane that was confirmed by surgical findings. In the second case, the use of real-time three-dimensional transoesophageal echocardiography (3D TEE) provided superb 3D visualization quality of the subaortic membrane and allowed assessing the stenosis area using the multiplanar review mode. Hence, the use of live real-time 3D TEE is likely to be key in the spatial assessment of this complex lesion.