Thirty-eight histologically confirmed desmoid tumors were treated with conservative surgical resection and interstitial iridium 192. Patients included in this series constituted a poor prognostic group. Seventy five percent (75%) had previous recurrences of their disease and 50% had tumors 8 cm or greater in size. In addition, 16% of the patients had gross residual disease after surgical excision and 79% had positive or close margins of resection. With a median follow-up of 5.5 years, the 5-year actuarial in-field local control rate was 75% and the overall local control rate was 66%. Four of the 12 local recurrences developed at the periphery of the implant volume and four patients failed at least 3 cm or more beyond the treated volume. After salvage therapy, the 5-year actuarial local control rate was 95%. Two patients required amputation for recurrent disease. Thirty of 34 patients remain free of disease with an excellent functional result achieved. The authors conclude that surgical resection and postoperative interstitial iridium 192 is effective therapy for patients with desmoid tumors. Despite the fact that most patients in this series had bulky, recurrent tumors, excellent long-term local control and limb function were achieved.