摘要Small bowel metastases from primary carcinoma of the lung are very uncommon and occur usually in patients with terminal stage disease. These metastases are usually asymptomatic, but may present as perforation,obstruction, malabsorption, or hemorrhage. Hemorrhage as a first presentation of small bowel metastases is extremely rare and is related to very poor patient survival. We describe a case of a 61- year old patient with primary adenocarcinoma of the lung, presenting with melena as the first manifestation of small bowel metastasis. Both primary tumor and metastatic lesions were diagnosed almost simultaneously. Upper gastrointestinal endoscopy performed with a colonoscope revealed active bleeding from a metastatic tumor involving the duodenum and the proximal jejunum.Histological examination and immunohistochemical staining of the biopsy specimen strongly supported the diagnosis of metastatic lung adenocarcinoma, suggesting that small bowel metastases from primary carcinoma of the lung occur usually in patients with terminal disease and rarely produce symptoms. Gastrointestinal bleeding from metastatic small intestinal lesions should be included in the differential diagnosis of gastrointestinal blood loss in a patient with a known bronchogenic tumor.