This book contains contributions from participants at a Porphyrin Photosensitization Workshop held in Washington DC on 28-29 September, 1981. There had been several prior such gatherings during 1979 and 1980, but the 1981 meeting was the most extensive to date with almost 200 attending. These periodic meetings are designed to enable workers in the field to exchange information and learn of recent develop- ments. The Workshop was supported by PHS grant CA 31188 awarded by the National Cancer Institute, DHHS. Additional funds from Coherent Inc. [Laser Division], Palo Alto, con- tributed to the success of this meeting as did the many ex- cellent presentations and discussions. Preparation of camera-ready copy from submitted manu- scripts was carried out via the Textedit computer program by Glenn Cummings, Amanda Cummings and David Kessel. Respon- sibility for final manuscript preparation rests with the editors. David Kessel Thomas J. Dougherty CONTENTS INTRODUCTION D. Kessel and T.J. Dougherty. . * * . * . * . * * 1 PHOTORADIATION THERAPY - CLINICAL AND DRUG ADVANCES 3 T.J. Dougherty, D.G. Boyle, K.R. Weishaupt, B.A. Henderson, W.R. Potter, D.A. Bellnier and K.E. Wityk INTRA-ABDOMINAL APPLICATIONS OF HEMATOPORPHYRIN 15 PHOTORADIATION THERAPY . * ...* . * * .