Body surface potential mapping systems have been developed by several laboratories in our country as well as many other countries all over the world. In most laboratories the basic procedure is the same. Body surface potentials are measured simultaneously using a multiplexer with or without sampling bold, with Wilson's central terminal and stored on a floppy disk in a digital form. Editing for waveform and drift of the baseline was performed in each leads and invalid leads were interpolated from surrounding leads values. Then, different types of maps such as isopotential map, isointegral map, isochronal map and departure map suitable for each clinical evaluation are constructed automatically. However, although body surface mapping provides detailed information about cardiac electrical activity, its clinical use has been limited by the following reasons summarized by B. Taccardi in 1985. 1) Lack of standardization: Different electrode replacement prevents comparing the results. 2) The equipment is comparably expensive. 3) Application of electrode is time-consuming. 4) Analysis of data is not standardized. Further clinical studies may improve some of above described difficulties. And the availability of high performance microcomputers and clinically acceptable electrodes are essential.