We evaluated bronchial arterial hemodynamics after thoracic irradiation therapy. We performed bronchial arteriography in 9 patients (8 males and 1 female) with lung cancer who received thoracic irradiation (58-72 Gy). Three patients had adenocarcinoma, 3 squamous cell carcinoma, 2 small cell carcinoma and 1 large cell carcinoma. Their clinical stages were 6 in stage IIIB and 3 in stage IV. Eight of these cases also received chemotherapy by intra-bronchial arterial infusion of anti-cancer agents (Carboplatin and/or Cisplatin). The bronchial arterial supply was patent except in the one complete remission case (small cell carcinoma of stage IIIB). In the five cases developing radiation pneumonitis, bronchial arteries demonstrated angiogenesis in the radiation fields, despite which pulmonary arteriography and/or pulmonary perfusion scintigrams showed a decreased pulmonary arterial supply. Bronchial arterial hemodynamics demonstrated no significant damage in the bronchial arteries by the thoracic irradiation therapy and/or bronchial arterial infusion of anti-cancer agents. It is suggested that patent bronchial arteries after radiation therapy promote local recurrences of lung cancer. In 5 cases, including 2 local relapsed cases and 3 cases showing no remarkable response to radical radiation therapy, we performed bronchial arterial infusion of anti-cancer agents after radiation therapy, with good responses obtained. We conclude that thoracic irradiation did not damage bronchial arteries as compared with pulmonary arteries, and that in local relapsed and radio-resistant cases bronchial arterial infusion of anti-cancer agents after radiation therapy is a useful approach.