Welcome to the proceedings of the 4th Workshop on Biomedical Image R- istration (WBIR). Previous WBIRs took place in Bled, Slovenia (1999), at the UniversityofPennsylvania, USA(2003)andinUtrecht, TheNetherlands(2006). This year, WBIR was hosted by the Institute Mathematics and Image Proce- ing and the Fraunhofer Project Group on Image Registration and it was held in Lub ] eck, Germany. It provided the opportunity to bring together researchers from all over the world to discuss some of the most recent advances in image registration and its applications. We had an excellent collection of papers...