BACKGROUND: Aggressive fibromatosis (AF) is a rare tumor of intermediate malignancy that has a strong potential for local invasiveness and recurrence. To date, there are no general recommendations for the clinical management of pediatric AF. METHODS: The authors retrospectively analyzed 94 patients aged 21 years, including 23 patients who underwent complete surgery (Group I), 42 patients who underwent incomplete surgery with microscopic residual tumor (Group II), and 29 patients who underwent either biopsy or macroscopically incomplete surgery (Group III). RESULTS: The 5-year event-free survival (EFS) and overall survival rates were 44% and 99%, respectively. Local recurrences developed in 22% of patients in Group I, in 76% of patients in Group II, and in 76% of patients in Group III. Two of 7 patients with abdominal disease died of tumor progression, whereas none of the patients with extra-abdominal AF died of their disease. Systemic treatment was given to 15 patients as first-line treatment and to 34 patients at time the time they developed recurrent disease: The response rate was 47% in the former patients and 50% in the latter patients. Objective responses were observed in 11 of 19 patients who received combined methotrexate plus vinblastine/vinorelbine, in 7 of 15 patients who received alkylating-agent chemotherapy, and in 4 of 11 patients who received other therapies (tamoxifen, sulindac, interferon alfa). CONCLUSIONS: The current analysis suggested that the clinical course of AF in children may resemble that of AF in adults. Local recurrences did not affect the chance of responding to systemic therapy or the survival rate. The completeness of initial resection was the main factor that influenced EFS, whereas disease control after marginal resection was much the same as that achieved after intralesional surgery/biopsy. Good responses to systemic treatments, and particularly to low-dose chemotherapy, were observed as reported previously in adults.