Abstract: A catheter for endocardial biopsy comprises a distal portion provided with biopsy forceps including two jaws which are movable relative to each other between an open position and a closed position, and means which are operable from the proximal end of the catheter for causing the movement of the jaws. The two jaws of the forceps are of electrically conductive material, are insulated from each other, and are connected respectively to two terminals situated at the proximal end of the catheter so that, when the jaws are in their open position, they can be used as electrodes for identifying the point of origin of a ventricular arrhythmia. It is thus possible to carry out an endocardial biopsy in apparently normal patients with ventricular arrhythmia, tissue samples being taken both in correspondence with the zone of origin of the arrhythmia and in correspondence with other zones, immediately after the identification of the zone of origin.