This book contains the written contributions to the 4th International Symposiumon Biomedical Simulation (ISBMS), which was held at Imperial College inLondon, UK, July 7–8, 2008.The manuscripts are organized in four different sections corresponding to keyareas and techniques of this constantly expanding field: finite element modeling,mass spring and statistical shape modeling, motion and fluid modeling and implementationissues. An additional section covers the posters presented at themeeting.