A total of 305 patients with community-acquired pneumonia have participated in comparative or non-comparative studies involving cefetamet pivoxil. Of these, 211 (55 adults and 156 children) were involved in a series of open, prospective, comparator-controlled, multi-centre studies. Adults were randomized to receive either cefetamet pivoxil 1000 mg twice daily or amoxycillin 750 mg 3-times daily for 10 days. Children received either cefetamet pivoxil 10 mg/kg twice daily, cefetamet pivoxil 20 mg/kg twice daily or cefaclor 10 mg/kg 3-times daily for 7 to 8 days. The remaining 94 patients were treated openly with cefetamet pivoxil, with most patients receiving cefetamet pivoxil 500 mg twice daily for an average of 10 days; an elderly sub-group of these patients aged 70 to 103 years received therapy for an average of 11 days. The main causative organisms isolated were Streptococcus pneumoniae and Haemophilus influenzae. In adult patients, a successful clinical outcome was achieved in 100% of assessable patients receiving cefetamet pivoxil 1000 mg twice daily, and about 90% in those receiving 500 mg twice daily. The success rate in children was 98% for both dose levels of cefetamet pivoxil and 90% for those receiving cefaclor. In elderly patients, the percentage was 78% for the 500 mg twice daily patients. Thus, the standard dose of cefetamet pivoxil (500 mg twice daily in adults, 10 mg/kg twice daily in children) was well tolerated and proved to be at least as effective as the comparator drugs which were given 3-times a day.