The use of preoperative radiation is well-established for soft tissue sarcoma, but its use in fibromatosis is not well-characterized. The purpose of this study was to examine the impact of preoperative radiotherapy on the local control of fibromatosis and to assess treatment-related morbidity in this setting. In particular we assessed complication rates in comparison with soft tissue sarcoma treatment. All patients with fibromatosis referred to this unit who received preoperative radiotherapy (50 Gy in 25 fractions) from 1988 to 2000 and who had at least 2 years of followup were included in this study. The rate of recurrence in this group was ascertained. Similarly constructed datasets from all patients with soft tissue sarcomas of the extremities who received preoperative radiation from 1986 to 1997 also were analyzed. The rates of complications in the two groups were compared. Fifty-eight patients were treated with preoperative radiation for fibromatosis and the median followup was 69 months. There were 11 local recurrences (19%). Major wound complications manifested in two patients (3.4%). Wound-related complications arose in 89 of 265 patients with soft tissue sarcomas (33.5%). There was a significant difference in the rate of major wound complications observed in the two groups. The use of radiotherapy before surgery is effective in the combined treatment of fibromatosis.