Objective To explore the method and efficiency of percutaneous transluminal septal tunnet myocardial ablation(PTSTMA) in treatment of 26 cases hypertrophic obstructive cardiomyopathy (HOCM) who were not suitable for conventional technology.Methods Firstly,we used a monorail Balloon which was slightly bigger than the interventricular septal branch of coronary artery and dilated it until posterior septal.After that,an OTW Balloon with larger size than the monorail was used to dilate again until made a " ventricular septum tunnel".Then,some alcohol was injected and PTSTMA was performed.Finally,we did the other and/or another interventricular septal branch by above method until the left ventricular outflow tract pressure gradient (LVOTPG) reduced ≥50％.The clinical indexes of the 26 cases HOCM immediately pest-operation of PTSTMA were observed and the follow up data during short term and metaphase were analyzed.Results The LVOTPG reduced ≥50％ in the26 cases HOCM,immediately after PTSTMA,the LVOTPG reduced from (75.6 ±22.4)mm Hg to (21.4 ± 5.8) mm Hg (t =11.94,P ＜ 0.01).At three months after ablation,the thickness of septal myocardium reduced from (22.8 ± 5.8) ram before ablation to (16.8 ± 4.2) mm(t =4.27,P ＜ 0.01),left atrium dimension reduced from(48.0 ±7.0) mm to (42.0 ±8.6) mm (t =2.76,P ＜0.01).Followed up 6.0to 60.0 months,the patients suffering from chest pain reduced from 14 cases before to 4 cases after the procedure(53.8％ (14/26) vs 15.4％ (4/26),x2 =8.49,P ＜ 0.01),the patients with expiratory dyspnea reduced from 26 cases to 5 cases(100％ (26/26) vs 19.2％ (5/26),x2 =35.22,P ＜ 0.01),NYHA functional class improved from (2.4 ± 0.6) to (1.4 ± 0.7) (t =5.53,P ＜ 0.01).Conclusion The PTSTMA was a supplemental method of PTSMA on treating HOCM,which was safe and useful during the short term and metaphase.