Employing a new catheter and technique complete retrograde left heart catheterization was accomplished in 96 of 100 consecutive patients. These 96 patients included 37 with ischemic heart disease, 13 of 17 with isolated aortic valve deformities, 11 with isolated rheumatic mitral valve deformities, 10 with combined rheumatic aortic and mitral valve deformities, and 25 with other problems. The only failures were in 4(of 27) patients with aortic valve deformities. No untoward complications occurred. The retrograde catheterization fluoroscopy time was usually less than 2 minutes. The shortest time was 44 seconds, the longest, 6 minutes and 2 seconds. These data indicate that this new catheterization method achieves safe, reliable (when the aortic valve is not deformed), simple, and rapid complete left heart catheterization. They further indicate it may be useful in assessing patients with mitral stenosis, pulmonary hypertension, hypertrophic obstructive cardiomyopathy, and left-to-right shunt problems.