The second edition of this book has drawn heavily on the first edition but a huge amount of research on steroid analysis has been published over the last 15 years. As a result, the Editors decided to let the first edition of this book stand on its own and direct readers interested in pre-1995 steroid analysis to it, simply because the post-1995 research can on its own fill the second edition. We have tried to keep a balance but equally have allowed authors of each chapter a significant degree of freedom to approach their particular topics as they thought fit – they are after all the experts in their field. We hope that readers will agree that we have got the balance right. In re-writing or updating these chapters, we have been greatly assisted by the developments in the availability of research publications electronically. Huge strides have been made in this area since 1995 and the ability to read a paper on one computer rather than trekking to the British Library is a tremendous advantage. The editors wish to express their gratitude to their respective insti- tions (St. Bartholomew and the Royal London School of Medicine, Queen Mary University of London and Kings College London) for providing us with el- tronic access to research journals from our home computers. Without such access, it would have been impossible to complete this book.