The 20th International Conference on Information Processing in Medical Imaging (IPMI) was held during July 2-6, 2007, at Rolduc Abbey, located in Kerkrade in the south of the Netherlands. Following the highly successful IPMI in Glenwood Springs in the Rocky Mountains, Colorado, USA (2005), the conference was the latest in a series of biennial scientific meetings where new developments in acquisition, analysis, and use of medical images are presented. IPMI is one of the longest running conferences in medical imaging. It was started in 1969 by a group of young scientists working in nuclear medicine. With a few iterations the conference expanded to other areas and became established as an important meeting for in-depth discussion of new methodological developments in medical imaging. Nowadays it is widely recognized as one of the most exciting and influential conferences in its field.