MAROTEAUX and Lamy,1 in 1962, defined pycnodysostosis as a syndrome consisting of the following characteristics: (1) dwarfism; (2) osteopetrosis; (3) partial agenesis of the terminal digits of the hands and feet; (4) cranial anomalies, such as persistence of fontanelles and failure of closure of cranial sutures; (5) frontal and occipital bossing; and (6) hypoplasia of the angle of the mandible. The literature has revealed that several cases of this syndrome have been published as other disorders, chiefly Albers-Schönberg disease and cleidocranial dysostosis. Still others will be considered under differential diagnosis. The first reported case appears to be that of Montanari2 in 1923. Collado-Otero,3 in 1956, accurately described a case as "another form of osseous dystrophy," and credit should be given to this author as well as to Maroteaux and Lamy for their recognition of this disorder as a distinct entity. Our literature survey yielded a total of