Acute bronchitis, although mostly caused by viral infections, is commonly treated with antibiotics. As antibiotics should only be prescribed upon strict indication, treatment options like a liquid herbal drug preparation from the roots of Pelargonium sidoides (EPs 7630) gain more and more interest. To evaluate the efficacy and safety of treatment with EPs 7630 in patients with acute bronchitis, a multi-centre, prospective, open observational study was conducted in 440 study sites located in Germany. A total of 2099 patients aged 0-93 years with productive cough for less than six days without indication for treatment with antibiotics were given EPs 7630-solution in an age-dependent dosage for 14 days. The primary outcome criterion was the mean change of the Bronchitis Severity Score (BSS: cough, sputum, rales/rhonchi, chest pain at cough, dyspnoea) from baseline to patient's individual last observation. During treatment, the mean BSS of all patients decreased from 7.1+/-2.9 points at baseline to 1.0+/-1.9 points at patients' individual last visit. Subgroup analysis for children showed a decrease of mean BSS from 6.3+/-2.8 points to 0.9+/-1.8 points and analysis of children younger than three years showed a decrease of mean BSS from 5.2+/-2.5 points to 1.2+/-2.1 points. Adverse events occurred in 26/2099 (1.2%) patients. Serious adverse events were not reported. In conclusion, EPs 7630 is an effective and well tolerated treatment of acute bronchitis in adults, children and infants outside the strict indication for antibiotic treatment.