The surgical treatment of obstructive hypertrophic cardiomyopathy has been a major area of clinical research in the Surgery Branch for nearly thirty years. The number of patients receiving surgical treatment has gradually increased in the past five years. Currently three procedures are performed: left ventricular myotomy and myectomy (LVMM), mitral valve replacement, LVMM + plication of the anterior leaflet of the mitral valve. The standard procedure was performed in 3 patients, MVR in 3 and the combined operation in 13, in one patient a LVMM and MVR was performed. An additional program has been the use of the automatic internal cardiac defibrillator for patients with a history of sudden death and who are refractory to all anti-arrythmic agents during electrophysiologic testing. The postoperative data has shown that excellent relief of obstruction at rest is obtained by all three procedures. Mitral valve replacement appears to provide a more predictable relief of obstruction with provocation. There are too few patients who have had long-term studies with the new procedure for comparison to the other groups.