The fourth biannual Gordon Research Conference on Vitamin B12 and Corphins will be held August 2-7, 2009, at Magdalen College, Oxford (UK). This conference is a multidisciplinary meeting that alternates between this European site (in 2005 it was held in Oxford) and the sites in the United States (in 2007 in Biddeford, Maine), reflecting the sizeable communities in the field of vitamin B12 and Corphins on both continents. The Chair of the 2009 meeting is Bernhard Kr[unreadable]utler, Professor of Organic Chemistry at the University of Innsbruck in Austria, with the vice- Chair being Prof. Catherine L. Drennan from the Massachusetts Institute of Technology (MIT), Cambridge, MA USA. The aims for the 2009 meeting are: 1. To feature a group of scientists from widely different fields including epidemiology, toxicology, genetics, biochemistry, microbiology, chemistry, and physics. All of them are working at the forefront of research in the fields of vitamin B12 and corphins. The topics presented will vary from disease models, nutrition, B12 uptake and transport, to mechanisms of enzyme catalysis with B12-cofactors and corphins. 2. To organize an exciting and stimulating conference in which the members of the different communities and seniorities actively participate, discuss the latest and hottest developments and most importantly, share insights obtained from diverse viewpoints and backgrounds. The increased multidisciplinary interactions are also intended to promote collaborations. 3. To ensure a continuing influx of new ideas and investigators. To achieve this, the speakers list has been made up mostly of speakers that have not spoken before or recently and several junior and other scientists, in particular postdocs, have been identified that will present on their work. The vitamin B12 cofactor, discovered as a result of the search for the cause of pernicious anemia, plays an important role in medicine. Conditions such as methylmalonic aciduria and homocystinuria are inborn errors of vitamin B12 metabolism. In addition, B12 nutritional deficiencies in the elderly are linked to dementia.