Abstract: AIM To evaluate the clinical effects of modified Morrow’s procedure on patients with hypertrophic obstructive cardiomyopathy (HOCM). METHODS From August 2013 to July 2014, 21 HOCM patients9 males and 12 females, ages ranging from 22 to 64 years, mean (45.3±11.9) yearrsunderwent modified Morrow’s procedure including extensive myectomy and isolation of mitral papillary muscle. Two patients underwent plication of the anterior mitral leaflet. All patients underwent echocardiography before operation and discharge to examine the location and degree of left ventricular outflow tract(LVOT)obstruction, mitral valve apparatus and associated cardiovascular malformation. Transesophageal echocardiogram (TEE) was done in each patient introperatively. RESULTS No deaths occurred in hospital. The weight of myocardium resected ranged from 8.5 g to 22.8 g with a mean of (14.9±3.8) g. III° heart block occurred in one patient and a permanent pacemaker was implanted before discharge.Systolic anterior motion (SAM) disappeared in all cases.Chest pain and shortness of breath disappeared in 19/21 patients. Compared with those pre-operatively, pressure gradients of LVOT obviously decreased(101.3±40.9) mmHg vs.(9.6±7.5)mmHg, P<0.01,LVOT diameter enlarged significantly(5.0±2.1) mm vs.(16.6±3.6) mm, P<0.01,size of the left atrium decreased remarkably(47.0±5.4) mm vs.(41.8±5.3) mm,P<0.01and mitral regurgitation improved obviously(5.9±3.7) ml vs.(1.8±1.5) ml, P<0.01.Heart function improved in all patients postoperatively and 90% of the patients were in NYHA functional class I with no severe complications.CONCLUSION Modified Morrow’s procedure is an effective method for treatment of hypertrophic obstructive cardiomyopathy. After operation, LVOT obstruction can be relieved in all patients and mitral valve function can be significantly improved.