17 hospitalised patients with a wide variety of common lower respiratory tract infections received at least 6 days of intravenous bolus cefoperazone 1.0g 12-hourly. Disease was caused by Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, and mixed anaerobes in 1 patient. All isolates were sensitive to cefoperazone. 11 patients were cured, 4 improved, and 2 failed (1 of whom had an anaerobic empyema). Toxicity and side effects were infrequent. In general cefoperazone was effective therapy for these infections.