Recurrence of persistence of heart failure in patients after mitral and aortic valve replacement is a difficult diagnostic problem. Clinical evaluation and noninvasive tests cannot always distinguish poor left ventricular function from paraprosthetic leak or persistent pulmonary vascular disease. Full evaluation by cardiac catheterisation may then be necessary but is difficult because of the inaccessibility of the left ventricle. Under these circumstances, left ventriculography by direct transapical puncture is an alternative to crossing the prosthesis by a catheter and may be the only way of obtaining diagnostic information. We describe our experience of left ventriculography by percutaneous transapical passage of a flexible angiographic catheter (as distinct from a rigid angiographic needle) in 15 such patients (on 16 occasions). Non-fatal complications occurred in three patients. The information thus obtained allowed a clinical decision to be made and distinguished the inoperable from the operable group. Surgery was subsequently performed in seven patients with beneficial results.