The authors in October 1975 encountered a case that visited their hospital with the chief complaint of deformity of both middle fingers. The case closely resembled brachyhyperphalangism, but no definite diagnosis could be obtained as a findings suggestive of deltaphalanx was present in some phalanges and some ·took the view that polydactylous change of the middle finger was suggested. However, because numerous deltaphalanges were found in both index and middle fingers in a younger sister bone five years later, both of the cases were diagnosed as belonging to the category of what hand surgeons of Japan maintain is cleft hand group. However, there are literature which describe cases like these two as typical cases of brachydactyly, and it was considered that study would have to be made in future whether brachydactyly and cleft hand group had some parts of their developmental mechanism in common or whether the concept of brachydactyly is as yet unestablished.