Peripheral facial paralysis is a diagnostic challenge. Because 10% of the patients referred with a diagnosis of Bell’s palsy were found to have a treatable, progressive, or life-threatening lesion, effort should be made to diagnose the cause. Acute facial palsies are mostly “idiopathic” (Bell’s palsy) but it is a diagnosis of exclusion; therefore, cases of acute acquired, isolated peripheral facial paralysis should be investigated thoroughly. The purpose of this article is to explain the principles of the ultrasound techniques; outline the procedures, measurements, and interpretation of the results; evaluate the reliability and validity of this method for meaningfully measuring inflammatory responses; and highlight the advantages and limitations of ultrasonography in patients with Bell’s palsy.