Flomoxef (FMOX, 6315-S) was used in the treatment of 10 patients (male 8, female 2) with respiratory infections, and clinical responses and side effects of FMOX were evaluated. The mean age of the patients was 68.2 years, and the mean body weight was 45.8 kg; this background of the patients indicates that most of them were elderly, and light in body weight. FMOX was administrated by drip infusion in 1 g doses twice daily in all the cases. The mean duration of FMOX therapy was 14 days, and the mean total dose administered was 28 g. Efficacy rate was 80% in the 10 cases. Adverse reactions were not observed and no abnormalities in laboratory tests were detected. In conclusion, FMOX is an effective antibiotic in the treatment of aged patients with respiratory infections.