IPMI occupies an important position in the scientific calendar. Every two years, it brings together leading researchers in medical image formation, analysis and interpretation, for an international workshop that allows extensive, in-depth d- cussion of new ideas. Many of the most influential developments in the field were first presented at IPMI, and the series has done much to foster a rigorous scientific approach to information processing in medical imaging. IPMI 2003 was held over 5 days in July 2003 at St. Martin’s College, - bleside, in the heart of the English Lake District. Full papers were invited on any aspect of information processing in medical imaging, with particular - couragement for submissions exploring generic mathematical or computational principles. Recognizing the rapidly evolving nature of the field, we encouraged a broad interpretation of medical imaging : from macroscopictomolecular imaging; from applications in patient care to those in biomedical research. We received 123 submissions by the deadline in February 2003. Each paper was reviewed by four members of the Scientific Committee, placing particular emphasis on originality, scientific rigor, and biomedical relevance. Papers were selected for the meeting by a Paper Selection Committee, based on reviewers’ rankings and theirdetailedcomments. A total of 28 papers were accepted asoral presentations and 29 as posters. Unfortunately, the standard was so high that we had to turn down many excellent papers.