In 280 patients with stage II breast cancer, chest X-ray was performed at 6 and 12 months and yearly thereafter to the 6th year or until recurrence, another cancer was detected, the patient refused further follow-up or died. Among 1289 scheduled chest X-rays, malignant changes were found in 20 patients, of which only 3 had pulmonary symptoms. In a further 14 patients malignant changes were suspected, but follow-up examinations could not prove malignancy. 26 patients presented within 12 months after the last scheduled X-ray with pulmonary symptoms and a work-up chest X-ray revealed malignant changes. Thus, in only 1.3% of the scheduled X-rays were unsuspected malignant changes diagnosed. Median survival of patients with malignant chest X-rays found at scheduled controls versus between scheduled controls did not differ significantly (P = 0.26). It is concluded that routine chest X-ray is not indicated in patients with stage II breast cancer.