The authors' experience with computed tomography guided excision of osteoid osteoma in an outpatient setting using an Einhorn biopsy set and a power drill in 21 patients is described. In the last 5 years, 21 patients aged 7 to 51 years who had radiographic findings and symptoms of osteoid osteoma were included in the study. The nidus of the tumor was excised successfully in all cases using a coaxial technique with a power drill. Excision of the nidus was confirmed by postexcision computed tomography scans, histologic evaluation, and absence of symptoms on clinical and radiographic followup. Only one minor complication and no recurrences occurred with a mean followup of 17 months (range, 9-43 months). Percutaneous computed tomography guided excision is an effective, safe, and cost effective method of treatment of osteoid osteoma.