Left ventriculography with RAO projection gives many informations about the states of mitral apparatus and ofleft ventricular function. The knowledges about these are very important to determination of performance, time andmethod of cardiac surgery in mitral valvular heart diseases. 20 patients of mitral valvular heart disease werestudied with left ventriculographies in RAO projection which were taken before open heart surgery at department ofradiology, National Medical Center during 1976 to June 1980, Comparing with operative findings and pathologicspecimens. The results are as follows; 1. Poor motilites and irregularities of mitral valves which were visibleabove the fulcrum, and irregularites and severe retraction of the fornix during left ventricular systolic phaseson left ventriculographies were compatible to the stage III by Sellers' classification of mitral valvular stenosison operative findings. Mild degree of irregularities and restriction with smooth fornix suggested the stage I. Thefindings between these two, the stage II. 2. MI group showed left ventricular dilation without hypertrophy, MSgroup, no significant effect on LV, Ao group, enlargement with hypertrophy. 3. In MS and MI groups, ejectionfraction were relatively well preserved unitl grade I-II of NYHA Classification. But grade III-IV revealeddecreased ejection fraction. E.F. was below 0.55 in 86% of grade III-IV. In Ao group, grade IV showed wellpreservation of E.F. 4. The pattern of left ventricular contraction demonstrated hypekinetic synesis or asynesisin 44.4% of grade IV, but was normal in all cases below grade III. Hyperkinetic synesis was visible in all Aogroup. 5. Left ventriculography is essential to evaluation of mitral valve apparatus and LV function in mitralheart diseases before cardiac surgery.