A clinical, retrospective and non-comparative study was undertaken to assess the clinical efficacy and tolerability of azithromycin in the treatment of community-acquired pneumonia caused by Legionella pneumophila. A total of 16 patients with a serologically confirmed diagnosis of Legionnaires' diseases were included. Azithromycin was administered orally at a total dose of 1.5 g for either 3 or 5 days. All patients were no side-effects requiring discontinuation of the treatment. Further increase of abnormal baseline liver function was recorded in 2 patients and in 1 patient mild, transient eosinophilia. Equal clinical efficacy and tolerability were observed with the 3- and 5-day dosage regimen. These results indicate that azithromycin given at a standard dose of 1.5 g is effective and well tolerated in the treatment of Legionnaires' disease.