Objective To determine the morphological characteristics of hypertrophic obstructive cardiomyopathy(HOCM) patients by left ventriculography.Methods A total of 74 patients with hypertrophic cardiomyopathy(HCM),who got a definite diagnosis by ventriculography and ultrasonography,were enrolled.The patients with left ventricular outflow tract pressure gradient ≥ 30 mmHg was categorized as HOCM group,those ≤30 mmHg as hypertrophic nonobstructive cardiomyopathy(HNCM) group.The morphological characteristics and ventriculographic results were compared between the two groups.Results(1) In 74 patients,there were 14 cases(18.9%) of HOCM(6 cases of systolic anterior motion,3 cases of coronary heart disease) and 60 cases(81.1%) of HNCM(11 cases complicated by coronary heart disease).(2) Ultrasonography showed that left ventricular(LV) septal wall thickness was(11.4±2.5) mm,posterior wall thickness(9.8±1.7) mm,LV end-diastolic inner diameter(LVEDD)(48±5) mm,left atrial(LA) anterior posterior diameter(36±5) mm.(3) Left ventriculography demonstrated that LV end-diastolic volume(LVEDV) was(123±31) ml,LV end-systolic volume(LVESV)(27±11) ml,LV ejection fraction(LVEF)(78±6)%.(4) According to morphological characteristics revealed by left ventriculography,there were 14 cases of HOCM,including 5 cases with normal LV structure,and 60 cases of HNCM,including 27 cases with normal LV structure.Conclusion There is no significant difference between HNCM and HOCM groups in LVEDD,LVEDV,LVESV,LVEF,and number of cases with normal LV morphological characteristics.