The CO2 laser was evaluated to determine its effectiveness for marginal cauterization of giant-cell tumors after resectional curettage. Average power densities of 11-53 W/cm2 for corresponding application times of 120 and 60 seconds were found to produce 30° temperature rises in fresh human femoral heads. This temperature was adequate to achieve thermal necrosis of the tumor margins to a depth of 5 mm. CO2 laser resection was found to be accurate and reproducible. No damage to underlying hyaline cartilage and soft tissues was evident histologically at one and four weeks after experimental local laser cauterization of distal femoral condyles in rabbits.