Turner syndrome (45,X karyotype) is one of the few sex chromosome aberrations that can be recognized clinically during infancy or childhood. The features are short stature, broad shield chest, lymphedema of feet and legs, and webbed neck. On the other hand, boys with 47,XYY karyotype cannot be diagnosed from the clinical manifestations. Although the clinical features in Turner syndrome have been the subject of many reports, there have been few anthropometric studies on patients with Turner syndrome during childhood, and there have been no such studies on 47,XYY boys. This study was designed to determine the anthropometric characteristics of 11 patients with Turner syndrome diagnosed at the University Hospital, University of Tokyo, and 7 patients with 47,XYY found in a newborn survey in one maternity hospital in Tokyo.