The 8th International Conference on Medical Imaging and Computer Assisted Intervention, MICCAI 2005, was held in Palm Springs, California, USA, at the Riviera Resort, October 26-29, 2005. MICCAIhasbecomeapremierinternationalconferencewithin-depthpapers on the multidisciplinary ?elds of medical image computing, computer-assisted interventionandmedicalrobotics. Theconferencebringstogetherclinicians, b- logicalscientists, computer scientists, engineers, physicists and other researchers and o?ers them a forum to exchange ideas in these exciting and rapidly growing ?elds. The impact of MICCAI increases each year and the quality and quantity of submitted papers this year was very impressive. We received a record 632 full submissions (8 pages in length), an increase of 22% from 2004, from 36 di?erent countries and 5 continents (see ?g. 2). Based on a decision of the MICCAI board, this year's conference employed a double-blind review procedure on a trial basis. Our Program Committee was made up of 11 area chairs, each of whom supervised the review of almost 60 papers. Four reviews were generated for each paper from 262 reviewers and the area chairs. A ?nal paper selection meeting took place during two days in early June 2005 in Chapel Hill, North Carolina. We are especially grateful to Elizabeth Bullitt, Polina Golland, David Haynor, Rasmus Larsen, Greg Hager and Daniel Ruc ] kert, who attended this meetingandhelpedusmakethe?nalselections. MartinStynerprovidedvaluable help with information management and the Web-site, and James Stewart is acknowledgedforreliableandtimelysupportoftheWeb-basedreviewingsystem. Wearegratefultoeveryonewhoparticipatedinthe reviewprocess;theydonated a large amount of time and e?ort to make these volumes possible and insure a highlevelofquality.