Dermatoglyphic studies were carried out on the congenital hand anomalies. Clinical materials consisted of 94 cases with hand anomalies and 148 of their normal relatives as a control. An analysis of the dermal ridge patterns was based on "the Memorandum of Dermatoglyphic Nomenclature" described by Penrose. The results were as follows: 1) In hypoplastic fingers, a high incidence of radial loops or arches was noted, which were quite rare in normal fingers. 2) In cases with crooked fingers, a high incidence of simian creases on palms was noticed. 3) In hypoplastic thumbs, higher positions of axial triradii were observed in accordance with the advance of their grades. 4) In cases of cleft hands with the loss of a central digit, a rudimental finger pattern was found on the edge of the cleft. In the absence of two digits in cleft hands, two finger patterns were found locating on either sides of the clefts of the palm. 5) In cases of syndactyly, union of the digital triradii was found on the palm between bases of the two syndactylous fingers. In a case of osseous syndactyly, single finger pattern was observed on the palmar side of the digital phalanges. 6) In congenital amputations of the humerus, rudimental digits or finger nubbins were sometimes found on their stumps. I found whorl patterns on the nubbins, which suggested rudimental finger patterns. 7) In unilateral constriction band syndrome, the finger and palm patterns showed no particular changes except coarse ridges on affected fingers. In macrodactyly, there were normal ridge counts and the increased ridge breadths, which might indicate the anomalies occurring after the stage of formation of finger patterns. 8) In families of the arthrogryposis multiple congenita and camptodactyly, total ridge counts were markedly decreased and the incidence of the arches on fingers was marked increased. Conclusions The studies on dermal ridges on the congenital hand anomalies may give important keys for solving the process and time of occurrence of these anomalies in the early embryonal lives.