From July 1991 to December 1993, 58 patients with Nonsmall cell lung cancer were randomly divided into hypoxyradiotherapy group (32 patients) and radiotherapy alone group (26 patients). Both groups received the sme radiotherapy with radiation dose of D T 65～70 to cancer of lungs. In hypoxia group, 10.5% oxygen gas mixture was inhaled during the therapy per session. The results showed that tumor response rates, immediate survival rates, skin and systemic reactions were similar in both groups. Hemogram was normal in both groups. In the hypoxyradiotherapy group, radioreaction of lungs, esophagus and trachea were milder than radiotherapy alone group (P