1. A brief historical outline of the gradual recognition of hereditary onycho-osteodysplasia is given.

2. A family, three members of which show the characteristic changes, is reported.

3. Forty-four families exhibiting the syndrome have been collected from the world literature; the whole series comprises over 400 affected persons, details being available for only 252 of them. The latter group has been analysed in order to find the relative incidence of the individual anomalies comprising the syndrome and of the different combinations in which they occur. It is suggested that the pelvic anomalies occur more frequently than has previously been believed.

4. An account is given of various other abnormalities recorded as occurring in association with the main tetrad of lesions. With few exceptions they are regarded as coincidental.

5. A brief account is given of the genetic factors involved.