In this volume I have attempted to cover the more important aspects of immunosuppressive therapy. In doing this, I have been very fortunate in securing the help of the distinguished authors who have contributed the chapters that follow and I am grateful to them for providing such thorough and up-to-date accounts of their subjects. Immunosuppression can be mediated by many hundreds of agents and it has been difficult to strike a balance between the 'small print' of drug action in animals and the useful­ ness or otherwise of drugs and other agents for inducing immunosuppression in patients. The first six chapters deal mainly with the experimental aspects of lmmunosuppression and include a full discussion of total lymphoid lrradiation and cyclosporin-A. Both these agents have shown great promise recently as forms of immunosuppression in animals and undoubtedly will come to be used more and more in patients recelvmg transplants of one form or another. The last four chapters are devoted to the use of the more traditional immunosuppressive agents for specific clinical conditions. In her chapter on renal transplantation, Dr McGeown describes in great detail not only the immunosuppressive regime she employs but the general manage­ ment of transplant patients. The clinical results have been so good in her unit that I felt her account should include these other aspects of treatment since they would seem to be just as important as the immunosuppressive regime she uses.