Each chapter of this volume is a contribution from an expert in the field, chosen by the editors to contribute to the 1997 Current Issues in Blood Substitute Research and Development course given in San Diego, March 17-19. The contributors were selected because of their expertise in areas which the editors believe to be critical to the advancement of the field, and which reflect activity in hot areas of relevant research. While there is a continuity in style for the annual course, each year brings changes in emphasis and content. In previous years, we were often not able to provide time for participants to present their views and opinions. Consequently, this year we encouraged discussion after each presentation. These sessions were recorded, transcribed, and are printed with the chapters herein. We believe that the product is very close to the capturing this year's course in print, and trust readers will enjoy reading the always candid and often provocative remarks from the audience. The price paid for inclusion of the discussion transcriptions was a delay in publication. Each author was allowed to edit his/her discussion section as well as the final version of the chapters prior to publication. The changes are mainly for grammar, and we tried, when possible, not to alter the conversational style of these interchanges.