A case of a 9-year-old boy with fibrocartilaginous mesenchymoma located in the distal femur is presented. Fibrocartilaginous mesenchymoma is a rare tumor. There have been 17 cases reported since 1984. The presenting complaint was pain and local discomfort. Radiological examination showed lytic and sclerotic lesions located in the distal femur. Magnetic resonance imaging showed that there was no soft tissue expansion. Differential diagnosis included fibrocartilaginous dysplasia, dedifferentiated chondrosarcoma, desmoplastic fibroma, fibrosarcoma and low-grade osteosarcoma. The diagnosis of the tumor in a state hospital would not have been possible. Wide resection of the tumor and resection arthrodesis with an intramedullary nail has yielded good results. The patient has been disease free for 4 years. Pathological diagnosis of this very rare tumor may be challenging; the treatment should be wide resection of the tumor.