Objective: Previous investigations suggest the use of extract from the root of Pelargonium sidoides (EPs 7630) for the therapy of uncomplicated acute upper airway inflammations, due to its strong antimicrobial and immunomodulatory effect. We aimed to compare clinical efficacy, safety and bactericidal effect of EPs 7630 and amoxicillin monotherapy in treatment of patients with mild to moderate acute bacterial rhinosinusitis (ABRS). Methods: Fifty ABRS patients were divided into two groups by randomization. Group 1 (n = 25) received EPs 7630 tablets, 3 × 20 mg/day per os for 10 days. Group 2 (n = 25) received amoxicillin tablets 3 × 500 mg/day per os, for 10 days. We assessed total symptom score (TSS), individual symptom scores for each symptom (nasal obstruction, rhinorrhea, postnasal drip, facial pain/pressure, loss of the sense of smell), endoscopic findings, including total endoscopic score (TES) and individual endoscopic signs (mucosal edema, mucopurulent secretion), before and after treatment. Samples of discharge taken from the middle meatus of all patients were cultivated for bacteria before and after therapy. Results: Higher absolute improvement after treatment was found for TSS, nasal obstruction, facial pain/pressure, impaired sense of smell, TES, mucosal edema and mucopurulent secretion in EPs 7630 group compared to amoxicillin group ( P < .001 for all parameters). However, there were no differences in absolute improvement of rhinorrhea score and postnasal drip score between groups ( P = .248; P = .679, respectively). Fewer types of bacteria grew on culture from middle meatal samples in EPs 7630 group compared to amoxicillin group. There were no reported adverse events from patients from either group. Conclusion: Our results demonstrated better clinical and antimicrobial efficacy of EPs 7630 than amoxicillin. EPs 7630 was shown as a potent agent and good alternative to antibiotic treatment of uncomplicated ABRS.