The whole-cell mode of the patch clamp technique was used to study Ca<sup>2+</sup>-activated Cl<sup>-</sup> current (I<sub>Cl</sub><sub>Ca</sub>) in gastric antral myocytes. Extracellular application of caffeine evoked Ca<sup>2+</sup>-activated current. In order to isolate the chloride current from background current, all known systems were blocked with specific blockers. The current-voltage relationship of caffeine-induced current showed outward rectification and it reversed at around E<sub>Cl<sup>-</sup></sub>. The shift of reversal potential upon the alteration of external and internal chloride concentrations was well fitted with results which were calculated by the Nernst equation. Extracellular addition of N-phenylanthranilic acid and niflumic acid which are known anion channel blockers abolished the caffeine induced current. Intracellular application of a high concentration of EGTA also abolished this current. Application of c-AMP, c-GMP, heparin, or AIF<sup>-</sup><sub>4</sub> made no remarkable changes to this current. Sodium replacement with the impermeable cation N-methylglucamine or with Cd<sup>2+</sup> rarely affected this current. From the above results it is suggested that the caffeine induced current was a Cl<sup>-</sup> current and it was activated by intracellular Ca<sup>2+</sup>.