Prosthetic treatment of bizarre congenital anomalies of the extremities in over 170 children was simplified by a classification based on the embryological somitic origin of the limb, well known to anatomists but heretofore ignored by clinicians. X-ray examination of the newborn allowed a plan of treatment which was reassuring to the distraught parents and which provided early, successful replacement of the involved extremity. Early acceptance of a prosthesis by the family and patient afforded a high degree of reestablishment of function. Improved artificial-limb construction techniques and materials, advanced occupational and physical therapy training methods, and utilization of basic surgical principles contributed to the 8-year study. The findings suggest that the classification scheme may aid materially in the discovery of the cause of congenital limb malformation.