Question: Is the effect of therapeutic ultrasound equally effective to antibiotic for treatment of sinusitis? Design: A randomized clinical trial with concealed allocation, self-assessment by the subjects and intention-to-treat analysis.

Subjects (n=48) with clinically diagnosed acute bacterial rhinosinusitis (ABRS)will included. The antibiotic group will receive amoxicillin (500 mg) 3 times per day for 10 days. The ultrasound group will receive therapeutic ultrasound over sinuses at 1.0 W/cm2 in continuous mode for 10 minutes once a day for 4 consecutive days. Improvement of symptoms (pain and congestion; numeric rating scale; 0-10) from day 1 to days 4 and 21 will be recorded. Relapses, side-effects and satisfaction with treatment will be assessed at one-year follow-up.

Inclusion Criteria:

• Pain when bending forward, headache, pain in the teeth, purulent nasal secretion, "double worsening" and white blood cell count (WBC).
• Patients eligible for the study had to meet one of the first three criteria (pain when bending forward, headache, pain in the teeth) and all of the other indicators (purulent nasal secretion, double worsening, a left handed displacement of lymphocytes and a right handed displacement of granulocytes on the WBC as indication of bacterial infection).
• Subjects over 15 years of age were included.

Exclusion Criteria:

• Subjects with any kind of antibiotic or allergic treatment within the last three weeks.
• Antibiotic intolerance.
• Pregnant women.