The motivation for this book was provided by The IUTAM Symposium on Flow in Collapsible Tubes and Past Other Highly Compliant Boundaries held on 26-30 March, 2001 at the University of Warwick. As this was the first scientific meeting on this research topic, the Scientific Committee considered it important to mark the occasion by producing a book. They did not wish to produce a conventional proceedings comprising a large number of brief articles of varying quality. Instead the present volume consists of twelve rigorously refereed and edited articles by invited authors who aim to sum up the state of the art in their particular research area. There are articles on flow in collapsible tubes, that include descriptions and discussion of biomedical applications; on instability of external, internal and rotating flows pas compliant walls; on the use of wall compliance for drag reduction and turbulence modification; and on dolphin hydrodynamics.