BACKGROUND: Acute rhinosinusitis is a frequent inflammatory disease of the mucosa of the nose and paranasal sinuses, usually associated with substantial morbidity having considerable socioeconomic impact. A new herbal drug based on a dry extract of a combination of 5 medicinal drugs (Sinupret(R) extract Dragees) was tested in a confirmatory trial in patients with acute viral rhinosinusitis. METHODS: 386 patients with symptomatic acute viral rhinosinusitis have been treated with the herbal drug combination (daily dosage 3 x 160 mg) or placebo in a double-blind, randomised, placebo-controlled clinical trial for 15 days. Primary efficacy endpoint was the investigator assessed symptom score at the end of therapy (Major Symptom Score, MSSINV). RESULTS: Treatment with verum lead to a statistically significant, clinically relevant improvement of the symptom score (2.07 +/- 0.18 [SEM] vs. 3.47 +/- 0.28 score points, p = 0.0001; PP: N = 300) compared to placebo at visit 5. The Number Needed to Treat (NNT) was 7 (PP). Adverse events occurred in 9.8% of the patients treated with verum and 14.1% of the patients treated with placebo. No serious adverse event was observed. The investigators assessed the tolerability of the herbal drug combination predominantly as good and very good (96.4% verum, 95.3% placebo). CONCLUSION: The results prove the efficacy and tolerability of the herbal drug in the indication acute viral rhinosinusitis. Especially due to the favorable benefit-risk ratio the drug represents a suitable treatment alternative.