We report a case of primary lung cancer in a 16-year-old boy. A histologic diagnosis of squamous cell carcinoma was made by bronchoscopic biopsy before surgery. The serum alphafetoprotein (AFP) level was markedly elevated at 193 ng/dl. Preoperative and postoperative evaluation revealed no evidence of scrotal mass. We performed right pneumonectomy with combined resection of the invaded portion of the left atrium under extracorporeal circulation. Despite the rapid improvement in the patient's general condition after surgery, the AFP level continued to increase without a transient decrease and reached 3160 ng/ml on the 23rd postoperative day. When the patient was readmitted because of dyspnea and headache on the 36th postoperative day, hypercalcemia of 13.9 mg/dl was noted, and this was resistant to subsequent treatment. The patient died on the 46th postoperative day.