This book constitutes the refereed proceedings of the 4th International Symposium on Biomedical Simulation, ISBMS 2008, held in London, UK, in July 2008.

The 19 revised full papers and 7 poster papers presented were carefully reviewed and selected from numerous submissions. The papers are organized in four different sections corresponding to key areas and techniques of this constantly expanding field: finite element modeling, mass spring and statistical shape modeling, motion and fluid modeling and implementation issues. An additional section covers the posters presented at the meeting.