The roentgen finding in young infants of cortical subperiosteal new bone formation, commonly involving the mandible, usually associated with an extremely variable course of fever, swelling, and irritability was identified as a new syndrome almost simultaneously by Caffey * and Smyth3about 10 years ago. Probably the first case of this disease was reported some 15 years before the reports of Caffey and Smyth, however, when Roske † described a single case of subperiosteal new bone formation involving the long bones and the mandibles in an infant boy. The syndrome was called infantile cortical hyperostosis by Caffey and was thought to be a benign disease of variable duration.4There was no mortality in the first 24 cases reported.5Later reports (which now include more than 70 cases) have listed several deaths from intercurrent infections ‡ and several instances of bony deformity.§ The syndrome was for a time confused