242 patients over 16 years of age with community-acquired lower respiratory tract infection (LRTI) were randomised to receive either roxithromycin 150mg twice daily or amoxicillin 500mg/clavulanic acid 125mg three times daily for 7 days, with a further 7 days if insufficient response was seen. Patients in each group were found to be well matched for age and gender. Intention-to-treat analysis showed that clinical response at 7 days was 69% for roxithromycin and 56% for amoxicillin/clavulanic acid (p = 0.05) and at study end was 91% for both treatment groups. There were fewer second treatment courses in the roxithromycin group (26vs38%, p = 0.04) and a shorter mean treatment duration (8.29 daysvs9.34 days, p>0.05). 12 patients (9.8%) on roxithromycin and 19 (17.1%) on amoxicillin/clavulanic acid had adverse effects possibly or probably related to the antibiotic (p>0.05). A prospective economic analysis showed that the benefit (difference between the 2 treatment costs) per clinical success was $A17.04 in favour of roxithromycin. Roxithromycin appears to be a more appropriate choice than amoxicillin/clavulanic acid for the treatment of LRTI in the community given the more appropriatein vitrospectrum, the efficacy against all common pathogens, greater cost-effectiveness, the more convenient dosage regimen, and because it is better tolerated.