We report the case of lung adenocarcinoma revealed by infected colonic tumor in a 62-year-old man. An en bloc surgical resection was performed with uneventful recovery. The pathologic report concluded in a right mesocolic lymph node metastases from a mildly differentiated adenocarcinoma from pulmonary origin. GI metastases of lung cancer are described in the literature and are frequently asymptomatic in patient with a known primary cancer. In this patient, the complication of the metastases revealed the primary and immunochemistry permitted to adapt the systemic chemotherapy.