Hemifacial spasm (HFS) is characterized by unilateral involuntary rapid and repetitive facial contractions, which interfere with the individual’s daily activities and social interactions. HFS is most frequently caused by compression of facial nerve at the root entry zone by an ectatic vessel. Differential diagnosis includes other etiologies (i.e., post-Bell’s palsy synkinesis, posterior fossa space-occupying lesions) and HFS mimics (i.e., blepharospasm and psychogenic movement disorders). Diagnosis is primarily clinical but may require imaging to rule out nonvascular etiologies (brain MRI) and to localize the nature and site of the vessel compression (brain MRA). Treatment of choice is botulinum toxin injections every 3–6 months. Surgical decompression has a high rate of success but may result in permanent complications (deafness, facial paralysis) in a small number of cases.