With the growth of digital and electronic i maging techniques in medicine particularly useful are the 3-D data for diagnosis and therapy. The representation of 3-D objects adopted uses the 'octree' data structure and is derived from serial section 2-D ima ges, as in CT. The slice-images, pre-proces sed with segmentation techniques and then processed to obtain quadtrees, allow by sim ple technique to reconstruct 3-D represen tation with octrees. For the movement analx sis and generation is adopted a syntax- di rected tree-transducer.The time-varying mages are represented by a sequence of 8-trees and the matching process is performed by parser. Many rules adopted for motion a nalysis and generation are described. Key-words: quadtree, octree, serial-section motion-primitive, tree-translation, parsing.