We have developed an efficient method for removing the vitelline membrane of Xenopus oocytes for patch clamp recording. Functional studies using oocytes as models provide insights into the biological profiles and physiological properties of ion channels. A methodological modification is described in this paper. The important feature of this modification is that protease treatment is used to remove the oocyte's vitelline membrane. This method is simple and the oocytes produced remain in a healthy state during the recording process. (C) 2004 Elsevier Inc. All rights reserved.