Summary. In this study, we investigated and analysed clinical efficacy and tolerability of moxifloxacin, a new quinolone antibiotic, for the outpatient treatment of bacterial respiratory infections – acute exacerbation of chronic obstructive pulmonary disease (AE-COPD), pneumonia and acute sinusitis. The study was post-marketing and observational, and was conducted after the registration and listing of moxifloxacin in commercial distribution in Croatia. A total of 84 physicians throughout Croatia participated in this study that included 440 patients, 231 with clinically confirmed diagnosis of AE-COPD, 103 with pneumo- nia and 46 with acute sinusitis. According to physicians, evaluation, 96.8% of the patients were cured. The improvement was recorded on the average after 3.2 days and cure after 6.4 days from the beginning of treatment. Adverse events (48 side effects) were recorded in 40 patients, most commonly suffering from milder gastrointestinal symptoms (nausea, diarrhoea). Serious adverse events were not recorded (phototoxicity, severe hepatic impairment, cardiotoxicity). Moxifloxacin tolerability and patient compliance during treatment were rated as excellent in three-quarters of the patients. Physicians stated they would again prescribe moxifloxacin in 415 or 94.3% of the patients.