A case of recurrent retroperitoneal desmoid tumor successfully treated with tamoxifen (Nolvadex tablets, ICI Pharma, Division of ICI Americas, Wilmington, DE) is reported. The patient presented late in her second pregnancy with a large retroperitoneal pelvic desmoid tumor that was treated with surgical excision and megestrol acetate. When the tumor recurred 12 months later, it was again treated with surgery, this time followed by radiation therapy. The desmoid tumor quickly recurred. The patient was then treated with tamoxifen, resulting in a complete tumor regression that has remained stable for 27 months. Tamoxifen should be considered as first-line therapy in recurrent desmoid tumors.