Cefoxitin was administered to a total of 17 patients with intractable bronchopulmonary infections who had failed to respond to other conventional antibiotics, and the following results were obtained. (1) The clinical response, except 1 patient classified as evaluation impossible, was excellent in 3 patients, good in 10 and fair in 3 with an efficacy rate of 81.3%. (2) An improvement rate of more than 70% was observed in the findings of body temperature, dyspnea, colour of sputum, WBC and CRP. (3) There was no subjective nor objective side effects attributable to cefoxitin. In view of the results stated above, we have concluded that cefoxitin is a useful antibiotic for the treatment of intractable bronchopulmonary infections.