A woman with a huge leiomyosarcoma of the duodenum that had invaded the pancreas and transverse colon is living and well 10 years after pancreaticoduodenectomy combined with resection of the transverse colon. Malignant potential of the tumor was determined by the mitotic rate and nuclear deoxyribonucleic acid content. The mass exceeded 10 cm yet was characterized by low mitotic activity and a near-diploid pattern. The long survival is attributed to the extensive surgery and low-grade malignancy of the tumor.