Duodenal metastases secondary to lung cancer are very rare and most of the time asymptomatic. When symptomatic they usually present with bowel obstruction or perforation. We here describe the case of a 68 year-old man with a solitary metastasis in the duodenum from a non-small cell lung carcinoma (NSCLC). The patient presented with reduced exercise tolerance and iron deficiency anemia without clinical gastrointestinal blood loss. Further investigation showed a tumor in the left upper lung lobe and a duodenal metastasis for which he received chemotherapy. To the best of our knowledge this is the first case report of iron deficiency anemia as initial presentation of a duodenal metastasis from a NSCLC.