Aggressive fibromatosis, also known as desmoid tumor or fibrosarcoma Grade I, desmoid type which occurs within deep soft tissues of the extremity or trunk is characterized by its aggressive invasiveness into soft tissues and high propensity for local recurrences. We have experienced sixcases of aggressive fibromatosis since September, 1983 and made clinical analysis after more than one year follow-up. Of the six cases, only one was male and the others were all females. Age distribution of the cases was two in first decade, two in third decade, one in fourth decade and the other one in sixth decade. Theree cases(50.0%), were arised in buttock and/or posterior aspect of proximal thigh, two cases in the back and the rest one case in flexor region of the forearm. The treatment offered were mostly wide local excision. Recurrences experienced out of these cases were four taking two thirds of the total, three of which were of buttock and posterior aspect of proximal thigh cases. Average time inteval between excision and apparent recurrence was thirteen months in average. For the recurred four cases, reoperation was done for two cases with good result so far, reoperation and radiotherapy for one case and reoperation plus radiation and chemotherapy for one case.