To compare the efficacy and safety of two different doses of levofloxacin with amoxycillin/clavulanic acid in the treatment of community-acquired pneumonia. A double-blind, randomized (1:1:1), double-dummy, three-arm parallel design, multicenter study was conducted in adult patients with mild-to-moderate community-acquired pneumonia. In total, 518 patients were randomized to receive levofloxacin 500 mg once daily, levofloxacin 500 mg twice daily or amoxycillin/clavulanic acid 625 mg three times daily for 7–10 days. The clinical cure rates post-therapy (2–5 days after the end of treatment) in the intent-to-treat population were 84.2% (144/171) in the levofloxacin once-daily group, 80.2% (142/177) in the levofloxacin twice-daily group and 85.7% (144/168) in the amoxycillin/clavulanic acid group. In the per-protocol population, the clinical cure rates post-therapy were 95.2% (138/145), 93.8% (137/146) and 95.3% (141/148), respectively. The total pathogen eradication rates were 97.8%, 100% and 97.5%, respectively. Both drugs were equally well tolerated and no major adverse events were observed. Levofloxacin was effective, safe and well tolerated in the treatment of mild-to-moderate community-acquired pneumonia. A complementary analysis indicated that there was no difference in therapeutic outcome between levofloxacin 500 mg once daily and twice daily. Levofloxacin 500 mg once daily, for 7–10 days, is an effective and safe treatment for mild-to-moderate community-acquired pneumonia in adults.