Desmoplastic fibroma is a very rare primary tumor of bone, closely related to aggressive fibromatosis of soft tissue. Although considered a benign lesion, it is locally destructive, can extend into the soft tissues, and has a high rate of local recurrences after incomplete surgical excision. Recognition of this entity is important to ensure proper surgical treatment. According to the published data, the tumor is most common in the long tubular bones (56%), the mandible (26%), and the pelvis (14%). Rib involvement by desmoplastic fibroma is extremely rare, and to our knowledge, only 3 cases have been reported in the literature to date. We present the case of a desmoplastic fibroma in the rib of a 19-year-old man, adding a fourth case to the previously reported cases involving this unusual location. The clinical history and the radiological and pathologic findings are presented.