ObjectiveTo compare clinical outcomes between modified and traditional Morrow procedures for the treatment of hypertrophic obstructive cardiomyopathy (HOCM). MethodsForty-two HOCM patients undergoing surgical correction in Beijing Anzhen Hospital between January 2005 and July 2011 were recruited in this study. According to different surgical techniques, all the patients were divided into 2 groups. In traditional Morrow procedure group, there were 16 patients including 13 males and 3 females with their age of 49±15 years. In modified Morrow procedure group, there were 26 patients including 14 males and 12 females with their age of 40±18 years. Preoperative and postoperative echocardiography were performed to compare ventricular septal thickness (VST), left ventricular outflow tract velocity (LVOTV)and left ventricular outflow gradient (LVOG)between the 2 groups. ResultsVST, LVOTV and LVOG of HOCM patients were significantly reduced after both traditional and modified Morrow procedure. There was statistical difference in preoperative and postoperative VST (23.10±3.64 mm vs. 17.38±4.39 mm), LVOTV (433.08±101.68 mm/s vs. 248.46±101.88 mm/s)and LVOG (78.57±40.16 mm Hg vs. 4.29±21.52 mm Hg)in traditional Morrow procedure group (P < 0.05). There was statistical difference in preoperative and postoperative VST (25.04±47.05 mm vs. 18.38±6.55 mm, P < 0.05), LVOTV (414.83±83.33 mm/s vs. 159.72±60.84 mm/s, P < 0.05)and LVOG (77.94±29.16 mm Hg vs. 17.56±9.39 mm Hg, P < 0.05)in modified Morrow procedure group (P < 0.05). Preoperative and postoperative difference in LVOG of modified Morrow procedure group was more significant than that of traditional Morrow procedure group (74.25±27.91 mm Hg vs. 34.63±30.66 mm Hg, P < 0.05). ConclusionModified Morrow procedure is superior to traditional Morrow procedure in reducing postoperative LVOG for HOCM patients.