The intraventricular multielectrode cardiac mapping probe comprises a catheter having an open proximal end and an open distal end and four elongate wire assemblies received in the catheter and having a distal end portion, and a proximal end portion extending from the catheter proximal open end. Each wire assembly comprises a tubing, six insulated wire conductors received in the tubing, and a central core wire which is stiff but yet flexible and which is received in the tubing and extends substantially the length thereof. A proximal connector is mounted on each tubing. The distal end portion of each wire assembly has six spaced apart sleeve electrodes thereon connected to respective ones of the wire conductors. The portion of each core wire in the distal end portion of one of the wire assemblies can be caused to assume a desired configuration after the wire assembly distal end portions are moved from a retracted position within the catheter to a position where the distal end portions are extended from the catheter and where the core wires can be caused to assume the desired configuration to form an elliptical envelope. The catheter is adapted to be inserted into an artery or vein to place the distal end opening thereof in a heart chamber from which the distal end portions of the wire assemblies can be extended to create the elliptical envelope and then can be incrementally rotated while electrical potentials are measured and recorded at different points along the surface of an endocardial wall of a heart chamber (e.g., ventricle) that come into contact with the sleeve electrodes.