A 62-year-old woman was referred to the hospital for close examination for anemia from her home doctor in August 2000. Laboratory data revealed anemia, thrombocytopenia and a rise in serum CEA. She was diagnosed as having sigmoid colon cancer with idiopathic thrombocytopenic purpura. She was treated with γ-globulin and platelet concentrate pre-operatively, and underwent sigmoidectomy and splenectomy on August 23 2000. The platelet count increased after operation, however, the response was temporary. In June 2001 and May 2002, she was treated with the pulse therapy of prednisolone which resulted in temporary remission. She was given low dose of prednisolone to maintain the platelet count. In November 2001, she was treated with eradication of Helicobacter pylori. The platelet count was increased and platelet-associated IgG (PAIgG) was decreased to normal range. This case suggests that the eradication of Helicobacter pylori may be useful for patients with ITP associated with cancer of the digestive organ.