This book is not a proceedings volume. Rather the chapters are essays by experts in the field of blood substitutes, invited by the editors to con tribute to the 1996 Current Issues in Blood Substitutes Research and Development course given in San Diego, March 18-21. The contributors were selected because of their expertise in areas deemed by the editors to be critical to the advancement of the field. The course, as in past years, is heavily influenced by feedback from par ticipants, and by research in this and related fields. In addition to the didactic lectures (for which these chapters are the foundation), the course also offers the opportunity for presentation of research reports, progress reports from the various companies currently commercializing products, and round table discussions of selected subjects. Thus, we are grateful to past participants for their helpful comments. Production of a book, especially on a short timeline, is not an easy feat.