Bronchial artery infusion therapy has been performed in a total of 27 patients by a selective catheterization technique chiefly as surgical adjuvant chemotherapy. A major antitumor agent chosen for this study was Mitomycin C. There was apparent tumor regression on the chest roentgenograms in 14 of 27 cases. The extent of tumor shrinkage ranged from 75% at maximum to 36% at minimum in 2 dimensional measurements on the x‐ray films. The patients were treated 1 to 4 times in a period of 2 days to 2 weeks. Observation periods after final infusion were limited to the term of preoperation. Subjective complaints were improved by the treatment. No serious side effects and very few complications were experienced. The authors would like to point out that the extent of tumor shrinkage may be related to the frequency of the infusion, and distant survival rate seemed to be better with the patients who received cancer resection after having recurrent infusion than with the patients having only one infusion.