This book consists of an edited report of the proceedings of the Fifth Cardiac Surgical Course run by the Royal Post-Graduate Medical School, The Institute of Cardiology, The Institute of Diseases of the Chest, The Institute of Child Health, The National Heart Hospital, The Brompton Hospital, The Hammersmith Hospital and Great Ormond Street Children's Hospital. These organisations encompass most of the major London hospitals associated with cardiac surgery. The course has been run annually, its aim being to help young men and women who are training in the specialised field of cardiac surgery. Thus this book consists of the proceedings of a teaching course rather than of a symposium, the 60 authors having been charged with the task of teaching rather than displaying their results or discussing their latest ideas and the proceedings reflect an interesting appraisal of the current status of cardiac surgery. The speakers were chosen from all over the world, because they were leaders in their field or because they have access to up to date and reliable information, and I am grateful to all the lecturers for their cooperation in the production of this volume. Ten thousand surgical cases are reported. These figures are drawn from experience in the United Kingdom, France, Germany, Switzerland, the United States of America, Australia and New Zealand. The reader may be surprised to find that only a handful of experiments are described.