Dynamic subaortic obstruction caused by septal hypertrophy may worsen the hemodynamics in some patients after heart surgery. Resection of the hypertrophied septum allows normal left ventricular function. We describe two patients with subaortic stenosis and a complicated postoperative course following heart surgery and additional resection of the subaortic muscular stenosis. One patient was reoperated because of residual obstruction of the left ventricular outflow tract; the postoperative course was uneventful thereafter. The second patient died after the primary surgery because of low output syndrome and sepsis. The postoperative management of this group of patients is difficult, demanding frequent assessment of the patient's hemodynamic condition and echocardiographic surveillance.