The two-volume set LNCS 3216 and LNCS 3217 constitutes the refereed proceedings of the 7th International Conference on Medical Image Computing and Computer-Assisted Intervention, MICCAI 2004, held in Saint-Malo, France in September 2004. The 235 revised full papers and 33 short communications presented were carefully reviewed and selected from a total of 617 submissions. The papers are organized in topical sections on brain segmentation, cardiovascular segmentation, segmentation, segmentation methods, registration, robotics, simulation and rendering, interventional imaging, brain imaging applications, and cardiovascular applications.