An inherited partial duplication syndrome of 17p is described. A comparison of the symptoms of a de novo partial duplication of 17p (Latta and Hoo, 1974) and those of our own case seems to indicate a characteristic syndrome. The main features include a small-for-date baby born at full term, small stature, microcephaly, typical facial changes, a heart defect, contractures of different joints, and deformities of the feet. The patients show severe motor and mental retardation.