In order to assess the efficacy and safety of amoxicillin-clavulanate for the treatment of anaerobic lung infection, 40 patients with lung abscess or necrotizing pneumonia were given sequential amoxicillin-clavulanate therapy. All patients received intravenous amoxicillin-clavulanate (2 g/200 mg/8 h), which was switched to oral form (1 g/125 mg/8 h) after clinical improvement. Mean duration of antibiotic therapy was 43.5 days. Microbiological documentation was obtained in 53% of cases. All but 1 of the 48 microorganisms isolated were susceptible to amoxicillin-clavulanate. The drug was well tolerated by the patients and no severe adverse effects were observed. At the end of treatment all patients were considered cured. The 35 patients assessed at long-term follow-up visit remained disease-free.