Case 1: A 52-year-old man underwent laparoscopic total gastrectomy for gastric cancer. After 2 years, a follow-up computed tomography(CT)scan showed a large, solid 10 cm-sized mass in his left upper abdomen. Under the diagnosis of a suspected mesenchymal tumor, a tumor resection with a partial resection of the upper jejunum and transverse colon was performed. Case 2: A 61-year-old man underwent laparoscopic pylorus-preserving gastrectomy for gastric cancer. After 1.5 years, follow-up CT showed a tumor of 2 cm in diameter near the greater curvature side of the upper stomach. Under the diagnosis of a suspected gastrointestinal stromal tumor(GIST), a laparoscopic partial resection of the stomach was performed. Histologically, spindle-shaped cells without atypia and rich collagen fibers were observed, and the sample was positive for b-catenin by immunostaining in both cases; from this evidence, the patients were diagnosed with desmoid tumors. Desmoid tumors have invasive proliferation characteristics, and treatment requires consideration of the balance between securing a surgical margin and increasing surgical stress.