The aim of this study was to describe clinical effectiveness of azithromycin in the management of lower respiratory tract infections in daily clinical practice, to examine duration of symptoms after therapy initiation, and to record any possible adverse effects of azithromycin treatment. A total of 153 patients were included in the analysis of the effectiveness of azithromycin: 94 patients with community acquired pneumonia (CAP) and 59 with acute exacerbation of chronic bronchitis (AECB). Clinical effectiveness was assessed as improvement, cure or failure after three-day treatment with azithromycin. The assessment was based on a calculation of clinical score for each diagnosis before treatment and on days 4, 10 and 28 after treatment initiation. Clinical effectiveness of azithromycin was 93.6% in CAP group and 94.9% in AECB group. Azithromycin led to relief of symptoms within three days in 88.6% of CAP patients and 77.2% of AECB patients. Overall, 15 adverse events were reported in 14 (9.1%) patients. The most common adverse events were abdominal pain, diarrhea and vomiting, each reported in four (2.6%) patients. Accordingly, azithromycin was found to have high clinical effectiveness and a small number of adverse events in the treatment of lower respiratory tract infections. ISRCTN38391551.