Synchronous development of gastrointestinal stromal tumors with other tumors in the digestive tract is relatively rare, and often occurs in the stomach. We report a 76-year-old woman, who suffered from the exceedingly rare synchronous development of small intestinal stromal tumor and cecal adenocarcinoma. The patient presented with intestinal obstructive symptoms. The pre-operative abdominal ultrasonography demonstrated a very large heterogenous periumbilical mass. Laparotomy was performed and the evaluation of the surgical specimen revealed a huge 14-cm subserosal mass of high risk ileal stromal tumor along with cecal adenocarcinoma with regional lymph node metastasis. The patient died within 3 months of diagnosis.