Dermatoglyphic abnormalities are often observed in patients with chromosome aberrations, but no similar observations have been made in animals. In the present study, palmar dermatoglyphics were examined in 4 rats with chromosome anomalies. Reciprocal translocations were induced by gamma-irradiation; the animals used were obtained from among offspring with abnormal karyotypes that were derived from the original mutant rats. As the epidermal surface of the volar pad of the rat is flat, dermatoglyphic characteristics were observed on the dermal surface following staining with toluidine blue. Unusual ridge configurations were found in some of them, suggesting that dermatoglyphic development in the rat reflects, to some extent, an abnormal chromosome constitution.