The presence of an extra Y chromosome in Man results in a condition termed the XYY Syndrome. Such individuals are tall, exhibit aggressive behavior, and may be mentally retarded. XYY patients are usually discovered after they have committed a crime. Even though relatively few XYY patients have been recorded so far in the literature the incidence of this condition in US males has been estimated at 1 in 300. Thus the majority of XYY's lead normal lives, directing their excess aggression into legal channels. For those who do not do so, the earlier corrective educational therapy is constituted the better the result. Since dermatoglyphics are affected by chromosomal aberrations there is a need to examine the dermatoglyphics of XYY patients in order to establish specific dermatoglyphic features that can be used for diagnosis at birth.