A 64 year old male was admitted to the Okayama University Medical School Hospital in June 1976. Although the patient had no subjective symptoms, the chest X-ray film revealed a tumor shadow in the left upper lung field. The tumor shadow was 8×9 cm, well demarcated, and homogenous. In 1969, at the time of an episode of pneumonia, the tumor shadow was 3×3 cm. At operation, the tumor was a chondrosarcoma of rib origin. The chest roentgenograms are described in this report.