A number of vital therapeutic modalities are not covered adequately in current dermatology textbooks. This book is intended to fill that gap. It originated in a series of special lectures on modem applications of physical modalities given at recent annual meetings of the American Academy of Dermatology; the main topics were radiotherapy, electrosurgery, phototherapy, cryosurgery, and related therapeutic modalities. The authors, recognized authorities in their field, have included much addi tional information which could not be covered in the original lectures because of time limitations. The indications for modem dermatological x-ray therapy reflect the basic views of the recently published guide lines of the National Academy of Sciences-National Research Council. Both text and illustrations are oriented toward the practical aspects of therapy with physical modalities. A special effort was made to bring the contributions up to date; pertinent references have been added for those who wish to pursue particular topics still further. Where there is an apparent overlap between chapters, it was felt to be advantageous because different authors approached their subject from different perspectives. I am most grateful to the various authors who generously contributed despite their many other commitments. I wish, also, to thank the staff of Springer-Verlag for their advice and assistance in the preparation of the manuscript.