In the surgery of the chest, we are often experienced pulmonary infections, so it is considered that the grasping antibiotic levels in pulmonary tissue is very important because of the decision of antibiotic dose schedule against pulmonary infections. For this purpose, latamoxef (LMOX) at a dose of 2 g was intravenously administered to 14 cases with pulmonary cancer, 3 cases with pulmonary tuberculosis, 2 cases with pulmonary abscess and 1 case with bronchiectasis, totally 20 cases and the concentrations in serum, pulmonary tissue, bronchia and sputum were measured up to 6 hours and the results obtained were as follows; The average serum concentration of LMOX was 137.2 micrograms/ml at 1/2 hour and decreased gradually, fell to 20.3 micrograms/ml at 6 hours. The average levels of LMOX in normal alveolus of pulmonary tissue and in bronchia were 63% and 48% of the serum level, respectively. The average level of LMOX in inflammatory alveolus of pulmonary tissue was approximately 20% lower than the normal alveolus. The average level of LMOX in sputum increased gradually and appeared 4.6 micrograms/ml at 6 hours. LMOX was shown a good results on the penetration into the pulmonary tissue and its level almost exceeded the minimal inhibitory concentration against clinical isolates from sputum of respiratory tract infections.