Current treatment for osteoid osteomas is usually surgical excision of the nidus. We treated 18 patients with osteoid osteoma by percutaneous thermocoagulation of the nidus under computed-tomography guidance. The procedure was technically successful in all cases and there were no complications. Patients were discharged on the following morning and resumed normal activities immediately. All patients but one remained pain free during follow-up (range 3-15 months). A second thermocoagulation treatment relieved the recurrent symptoms in this patient. Percutaneous thermocoagulation appears to be effective for osteoid osteomas, and is a minimally invasive alternative to surgical resection.