This book contains the written contributions to the 4th International Sym- sium on Biomedical Simulation (ISBMS), which was held at Imperial College in London, UK, July 7-8, 2008. The manuscripts areorganizedin four di?erent sections correspondingto key areas and techniques of this constantly expanding ?eld: ?nite element modeling, mass spring and statistical shape modeling, motion and ?uid modeling and - plementation issues. An additional section...