A turret exostosis is a rare complication of minor trauma to the dorsum of the fingers. In 1966, Wissinger reported first and called turret exostosis. Until now any case have not been reported in Korea. A twenty year-old man complained a painful mass on dorsum of the middle phalanx of the left 4th finger. Thirteen months ago, he had deep laceration of the left 4th finger and extensor tendon was ruptured totally with dorsal cortical breakage of the middle phalanx. Radiologically, there is a smooth, dome shaped, and well-defined osseous mass fused to the underlying bony cortex on the earlier injury site. This is a finding that suggest turret exostosis. We report a case and a brief review of literature.