Xenopus oocytes are one of the most widely utilized expression systems for voltage-dependent ion channels. Here, 1 describe a new technique for voltage-clamp recording of Xenopus oocytes that enables fast and stable monitoring of transmembrane current as well as intracellular perfusion by cutting a part of the plasma membrane to open the cytoplasm to the recording chamber which is filled with artificial intracellular solution. The original method was developed and described by Dr. E. Stefani and his colleagues, and I have modified it by employing a push-pull cannula to exchange the intracellular solution. The main features of this technique are: 1) High frequency response and relatively low current noise; fast activation and deactivation of ionic currents can be precisely evaluated. 2) Stable recording conditions lasting for several hours; this is a marked advantage over the conventional and patch-clamp recording. 3) Control of the ionic composition of both the internal and external media; the cut-open configuration enables desired manipulation of the internal milieu of oocytes easily, which is suitable for the study of Ca2+ channel modulation by second messengers and drugs.