Objective: To determine the effects of various doses of alcohol in pecutaneous transluminal septal myocardial ablation (PTSMA) for obstructive hypertrophic cardiomyopathy (HOCM). Methods: A 1∶2 matched case-control study was performed in our hospital. Ten consecutive patients with HOCM were assigned to receive small dose of alcohol(≤2.0 ml),and they were compared with 20 cases receiving standard doses(> 2.0 ml). Early results of hemodynamic changes and left ventricular remodeling were determined invasively and by echocardiography before and after PTSMA. Results: In low-dose alcohol group,left ventricular outflow tract pressure gradient (LVOTPG) was (28.0 ± 8.8) mmHg immediately after PTSMA (P < 0.01),and (29.5 ± 6.6) mmHg at 3 months (P < 0.01),versus (69.9 ± 13.1) mmHg before the procedure. In standard group,LVOTPG was(27.5 ± 7.2) mmHg immediately and (28.1 ± 5.0) mmHg at 3 months after PTSMA(P < 0.01),vs(70.6 ± 13.4) mmHg before the procedure. The thickness of interventricular septum (IVS) was significantly decreased at 3 months post-PTSMA in both groups(P < 0.01). However,there were no significant differences in hemodynamic and morphologic changes between the 2 groups after PTSMA. No significant correlations were identified between the volume of ethanol injected and early hemodynamic, morphologic variables immediately or at 3 months after PTSMA either in low or standard dose of alcohol. Conclusion: Low-dose of alcohol was able to achieve the desirable degree of LVOTPG reduction and left ventricular remodeling in PTSMA.