Septal myectomy is indicated in patients with obstructive hypertrophic cardiomyopathy (HCM) and intractable symptoms. Concomitant mitral valve (MV) surgery is performed for abnormalities contributing to systolic anterior motion (SAM), or for SAM-mediated mitral regurgitation (MR) with or without left ventricular outflow tract (LVOT) obstruction. One MV repair technique is anterior mitral leaflet extension (AMLE) utilizing bovine pericardium, stiffening the leaflet and enhancing coaptation posteriorly. Fifteen HCM patients who underwent combined myectomy-AMLE for LVOT obstruction or moderate-to-severe MR between 2009 and 2020 were analyzed using detailed echocardiography. The mean age was 56.6 years and 67% were female. The average peak systolic LVOT gradient and MR grade measured 73.4 mmHg and 2.3, respectively. Indications for myectomy-AMLE were LVOT obstruction and moderate-to-severe MR in 67%, MR only in 20%, and LVOT obstruction only in 13%. There was no mortality observed, and median follow-up was 1.2 years. Two patients had follow-up grade 1 mitral SAM, one of whom also had mild LVOT obstruction. No recurrent MR was observed in 93%, and mild MR in 7%. Compared with preoperative measures, there was a decrease in follow-up LV ejection fraction (68.2 vs 56.3%, p = 0.02) and maximal septal wall thickness (25.5 vs 21.3 mm, p 0.001), and an increase in the end-diastolic diameter (21.9 vs 24.8 mm/m{}^2, p = 0.04). There was no change in global longitudinal strain (–12.1 vs –11.6%, p = 0.73) and peak LV twist (7.4 vs 7.3{}^{\circ }, p = 0.97). In conclusion, myectomy-AMLE is a viable treatment option for carefully selected symptomatic HCM patients with LVOT obstruction or moderate-to-severe MR.