Clinical efficacy and safety of cefotiam were studied. Twelve patients with chronic sinusitis and 14 patients with chronic otitis media were intravenously given cefotiam in daily doses of 2 g for 7 to 10 days. In chronic sinusitis, clinical responses were excellent in 6 patients, good in 3 and fair in 3, the rate of satisfactory clinical responses (excellent and good) being 75%. In chronic otitis media, the responses were excellent in 5, good in 4 and fair in 5, the rate of satisfactory clinical responses being 65%. As for side effects, eruption and abdominal pain were observed in 1 patient.