The gastrointestinal tract (GIT) is an unusual site for metastasis. The rate of GIT metastases detected clinically is very low because of unspecific symptoms and signs of GIT involvement, which include general weakness, tiredness, weight loss, unspecific abdominal pain, fatigue, and anemia. We report clinical, endoscopic, and pathological patterns of two patients (malignant melanoma and primary lung tumor) with metastatic lesions in the gastroduodenum. The first case is a 59-year-old man with unspecific symptoms as nausea, vomiting and abdominal pain. He underwent resection of skin melanoma on his back one year before. Upper gastrointestinal endoscopy revealed two melanotic polypoid masses with ulcerations at the tip, one in the stomach and one in the duodenal bulb. Endoscopic biopsy of these polypoid masses and immunohistochemical stains confirmed the diagnosis of metastatic malignant melanoma. The second case is a 73-year-old man with a two-day history of melena and unspecific abdominal pain. Three weeks before, the patient was operated on for the adenocarcinoma of the lung. Endoscopy of the upper gastrointestinal tract revealed irregular polypoid mass with ulcerations at the tip: three of the stomach mucosa, two in the duodenal bulb and more than ten hemorrhagic polypoid masses at the desendent duodenum. Biopsies of these lesions confirmed the diagnosis of metastatic lung adenocarcinoma. In patients with a history of malignant melanoma and lung cancer unspecific symptoms, like abdominal pain, anemia, and gastrointestinal bleeding gastroduodenal metastases should be suspected. The diagnosis requires careful endoscopic examinations of the mucosa for metastatic lesions and biopsy with special immunohistochemical stains.