Chondroblastoma is a rare benign bone tumor. Treatment currently consists of curettage and bone graft. Prognosis depends basically on a relatively high rate of recurrence, between 5 and 38%, sometimes with local seeding of soft tissues and joint space. Such recurrences require wide resection with arthrodesis or even amputation. A 13-year-old girl with a humeral head chondroblastoma as treated by curettage and iliac bone graft. Six months later, a recurrence occurred with extension into the rotator cuff and the metaphysis. Remission was achieved by extensive surgical resection and hemiarthroplasty. The second case was a 14-year-old boy with a chondroblastoma of the right talus. He was treated by curettage and packing with bone substitute. After 2 recurrences with soft tissue and intra-articular extension, we performed a wide resection with reconstruction using a vascularized fibular graft. Many other cases in the literature illustrate such complications. We tried to find factors predictive of recurrence. Recurrence is observed when curettage was incomplete or when tumor cells were disseminated during surgery. Chondroblastoma is a benign bone tumor, but prognosis depends on the rapidity and severity of recurrence. Curettage should be as complete as possible and care should be taken to avoid contaminating the operative field.