Leiomyosarcomas of the duodenum are relatively rare and only some 330 cases have been reported in the Japanese literature. Among these duodenal leiomyosarcomas, tumors originating from the duodenal bulb represent only 10%. We experienced two cases of leiomyosarcoma of the duodenal bulb in which a segmental resection of the duodenal bulb was successfully perfomed. Patient 1, an 83-year-old woman, was found to have a submucosal tumor of the duodenal bulb during examination for marked anemia. Leiomyosarcoma of the duodenum was suspected and she underwent a segmental resection of the duodenum. Patient 2, a 69-year-old woman who had been followed up for a submucoal tumor in the duodenal buld for 9 years, was finally diagnosed as having a duodenal leiomyosarcoma. She underwent a segmental resection of the duodenum. The first patient is still alive 52 months after the operation and the other patient is also recurrence-free 13 months after the surgery. It is thought that segmental resection of the duodenum is appropriate treatment for leiomyosarcoma of the duodenal bulb.