Therapeutic effects of cefmetazole (cefmetazon, CMZ) were examined in 22 cases of bronchopneumonia. 2. Among the 22 cases, 17 cases (77%) showed better response than 'effective'. However, 10 cases (91%) showed better response than 'effective' if a daily of 4 g (11 cases) was taken into consideration. 3. No particular symptomatic side effect of CMZ was shown. Abnormality in such laboratory tests as transaminase (1 case of GOT, and 2 cases of GPT) and 1 case of alkaline phosphatase were observed, and the abnormality was ascribable to CMZ administration.