Background: We sought to analyze the pathological characteristics of hypertrophic obstructive cardiomyopathy (HOCM) with concomitant mitral valve abnormalities and to discuss the surgical treatment strategies. Methods: The clinical data of 26 HOCM patients treated from January 2014 to March 2016 were retrospectively analyzed. There were 19 males and 7 females with a mean age of 47 +/- 16 years (range, 10-70 years). Echocardiography showed HOCM, systolic anterior motion of the mitral apparatus, and concomitant mitral regurgitation. Modified Morrow procedure with expanded resection area was performed in 21 patients. Concomitant mitral valvuloplasty was performed in 4 patients, coronary artery bypass grafting was performed in one patient, and aortic valve replacement was performed in one patient. Echocardiography was performed intraoperatively at postoperative 1 week and at postoperative 1 year to evaluate the left ventricular obstruction and the mitral regurgitation. Results: The left ventricular outflow tract gradient, left ventricular outflow tract velocity, septal thickness, and mitral regurgitation area decreased significantly at postoperative 1 week and 1 year in comparison with the baseline (all P < .001). The postoperative mitral regurgitation and systolic anterior motion of the mitral apparatus were completely abolished or significantly relieved. Only one patient had moderate mitral regurgitation of 7 cm(2) after the surgery. At postoperative 1 year, all patients were asymptomatic, and the quality of life was significantly improved. The New York Heart Association (NYHA) class was I-II. Echocardiography showed good anatomy and function of the mitral valve. Conclusions: Concomitant mitral valve abnormality is not uncommon in HOCM. Septal myectomy can adequately expand the left ventricular outflow tract and abolish mitral regurgitation and systolic anterior motion of the mitral apparatus. Concomitant mitral valvuloplasty is indicated for severe congenital abnormalities or secondary lesions of the mitral valve, and the outcomes are satisfactory.