polluted by man-made sources of electromagnetic radiation with frequencies and magnitudes never before present. Man's activities have probably changed the earth's electromagnetic background to a greater degree than they have changed any other natural physical attribute of the earth. The evidence now indicates that the present abnormal electromagnetic environment constitutes a significant health risk. There are also positive aspects of the relationship between electromagnetism and life. Clinical uses of electromagnetic energy are increasing and promise to expand into important areas in the near future. This book synthesizes the various aspects of the role of electricity in biology.