The case of a patient who underwent a left lower lobe lobectomy for adenocarcinoma of the lung and developed a metachronous squamous cell carcinoma of the right lung eight years later, is presented. The unusual nature of the case is emphasized utilizing a review of the literature. The criteria for diagnosing metachronous carcinomas are presented and a unified terminology for such cases is proposed. The requirement for life‐long follow‐up of any patient with cancer is emphasized.