Twenty four cases of pathologically diagnosed aggressive fibromatosis of bone were reported. 17 patients were followed for at least 2 years. Among them 4 recurred and the histological findings of their lesional tissues obtained after recurrence remained benign; one case refused radical treatment and the second biopsy done at 3.5 years after the appearance of the tumor showed no malignant changes; but another case died of lung metastasis. The authors suggest that the criteria for final diagnosis of an aggressive fibromatosis of bone are as follows: Besides the pathological findings, the lesion does not recur or metastasize more than 2 years after operation or it does recur, but still shows benign features histologically. As for treatment, marginal or wide excision is the procedure of choice.