We analyzed the records and histopathological specimens of fifty patients who had had a previously untreated desmoid tumor. The patients were followed for at least two years (average, forty-eight months). Three patients had a biopsy and were managed with observation only, and three patients had radiation therapy only. Of the remaining forty-four patients, thirty-four were managed with an operation and ten, with an operation and radiation therapy. In the group that was managed operatively without radiation therapy, the resection was wide in thirteen patients, marginal in nineteen, and intralesional in two. At the most recent follow-up examination, there had been no local recurrence in eleven of the patients who had had a wide resection, ten of the patients who had had a marginal resection, and one of the patients who had had an intralesional resection. Thus, twenty-two (65 per cent) of the thirty-four patients had no local recurrence at the time of the latest follow-up. In the group of ten patients who had been managed with an operation and radiation therapy, eight had no local recurrence: the two who had had a wide resection, three of the four who had had a marginal resection, and three of the four who had had an intralesional resection. None of the fifty patients died of the disease.