This book represents the proceedings of the 3rd International Symposium on Body Surface Mapping (BSM) held at Nijmegen; the Netherlands, from 11th to 13th of June, 1985, under the auspices of the International Council on Electrocardiology. This meeting brought together a group of international scientists en- gaged in the field of the study of electrocardiographic body surface po- tentials. Previous meetings of this kind took place at Burlington, Vt; U.S.A. in 1972, organized by Rush and Lepeschkin, and in 1982 at Tokyo or- ganized by Yamada, Harumi and Musha. The special aims of this 3rd International Symposium were: - to take stock of recent theoretical, technical, clinical and analytical advances - to discuss and stimulate future developments with respect to internatio- nal cooperation - to discuss promising clinical applications of the BSM technique A number of scientists engaged in this field had been invited to parti- cipate in this meeting, either by presenting a formal, introductory lec- ture, or by presenting a poster devoted to their more recent work. The ~n- vitation list was made up following suggestions of the scientific com- mittee for this meeting, the members of which were: (Parma; Italy) Prof.Dr. B. Taccardi Prof.Dr. F.A. Roberge (Montreal; Canada) Prof.Dr. A. van Oosterom (Nijmegen; The Netherlands). The organizing committee noted with great satisfaction that almost all people invited were indeed able to attend.