Action potential recordings by suction electrodes are generally small, unstable, and replete with artifacts like afterpotentials and incorrect values of the action potential overshoot. These electrodes record from the surface of the tissue plug imbedded in the electrode opening. This plug was found to have high electrical impedance, which accounts for the undesirable features of the recordings. The improved electrode yields negative-going resting potentials, and action potentials of 70–80 mv, routinely and for periods of 3–4 hr. The value of the overshoot compares with that recorded by glass microelectrodes. Afterpotentials are absent. The improvement results from the fact that the recording wire bypasses the tissue plug and is presumably recording from live, if injured, cells. We corroborate the important finding (B. F. Hoffman et al. Am. J. Physiol. 196: 1297, 1959) that the falling limbs of action potentials recorded simultaneously by suction and microelectrodes are coincident. cardiac electrophysiology; suction electrodes and microelectrodes Submitted on December 12, 1963