The long-term results of patients undergoing myotomy/myectomy of the ventricular septum for obstructive hypertrophic cardiomyopathy are documented in 31 patients (15 women, 16 men, age range 21 to 80 years [mean 55]) with mean New York Heart Association functional class III to IV congestive heart failure, who underwent radical myotomy/myectomy at the Brigham and Women's Hospital from 1972 to 1991. Preoperative gradients by catheterization or echocardiography ranged from 26 to 240 mm Hg (average 96). There were no operative deaths. Two patients developed early postoperative complete heart block requiring a transvenous pacemaker. Clinical follow-up was 1 to 14 years (mean 6.5). All surviving patients were restudied by echocardiography and clinical examination. The mean postoperative functional class was II. Postoperative gradients ranged from 0 to 30 mm Hg (mean 4.5) (p less than 0.001 compared with preoperative values). There were 5 late deaths (low cardiac output in 2, stroke in 2, and acute respiratory failure in 1); 4 of 5 deaths occurred in patients with concomitant coronary artery disease. Survival at 10 years was 86 +/- 9%. There were no reoperations for subaortic obstruction.