Primary lung cancer is rare in childhood. An asymptomatic 15-year-old boy was found to have a solitary circular shadow by a mass chest photofluorographic survey. The clinical course strongly suggested malignant tumor. Lobectomy three months after the detection of the shadow showed squamous cell carcinoma. At present, 3½ years after surgery, the patient is healthy and attending school. Cases of primary lung cancer in childhood are reviewed.