Aggressive desmoid tumors present difficult problems among patients with Gardner's syndrome. Recently, attention has been directed toward metabolic or hormonal manipulation of these tumors. A 21-year-old woman with Gardner's syndrome was admitted because of recurrent abdominal wall tumors. She was treated with nonsteroidal anti-inflammatory drugs, tamoxifen, and ascorbate for seven months. During this therapy, CT scan showed a gradual increase in size of the tumors. Subsequent resection of the abdominal tumors and the colon was performed. Although these three types of drugs were administered to prevent postoperative recurrence, an abdominal wall desmoid tumor that invaded the mesentery developed within nine months. The known treatments, that is, chemotherapy, irradiation, and surgical resection are discussed in view of this experience.