A case of the Jansen type of metaphysial dysostosis, followed for fifteen years from childhood to the age of nineteen, is reported. Radiographs taken at five years revealed the characteristic metaphysial changes in all the tubular bones, especially those of the hands and feet. The acetabular and glenoid areas, the costochondral junctions and the sternal ends of the clavicles were also involved. Radiographs taken at nineteen years, however, showed only marked deformities, which shows that the involvement of the metaphyses can regress by the end of growth. Biopsy of the lower end of radius at the age of twelve revealed changes in the growth plate or physis, especially in the zone of resting cartilage. This finding suggests that cellular function in this zone is disturbed by some unknown mechanism. Hence, the term physial dysostosis may be more accurate than metaphysial dysostosis.