Rat small intestine exhibits spontaneous slow-waves and spikes in normal solution. When treated with 0.3 – 0.7 mM EGTA, in calcium free solution, normal rhythmicity disappears and fast rhythmic potentials of duration intermediate to slow-waves and spikes appear. These induced fast potentials are absent in sodium free solution and are eliminated by verapamil, a calcium channel blocker. Application of EGTA to cat, guinea pig, mouse, and toad intestine did not yield fast potentials. The fast potentials appear to result from sodium entering through channels usually used by calcium. The fast potentials may be a phenomena exclusive to rat small intestine.