Retrograde left cardioangiographic studies using Amplatz spring coil guide catheter were carried out in 30 cases of acquired mitral valvular diseases. Of these 12 cases were compatible with the clinical diagnosis which were made pre-angiocardiographically. Eighteen out of 30 cases were diagnosed as pure mitral stenosis or mitral insufficiency which had been clinically diagnosed as mitral stenoinsufficiency or mitral stenosis with aortic insufficiency. The rate of difference is 60%. Twenty-five cases or 83% of all cases were operated. Of these 6 cases, the degree of regurgitation through the mitral valves were able to be evaluated cardioangiography and were confirmed by open heart operation. The retrograde left cardioangiography is considered to be a useful tool in conclusive dianosis of clinically equivocal mitral valvular diseases.[KTCS 1969;1:77-84]