A 64-year-old female was admitted with a 6-year history of right hemifacial spasm. Neurological examination and precontrast computed tomographic (CT) scanning showed no abnormality. Vertebral angiography disclosed, however, a small arteriovenous malformation (AVM) in the right cerebellopontine angle. A postcontrast CT scan demonstrated a high-density area in the right cerebellomedullary junction which appeared as a flow-void signal on magnetic resonance images. A right retromastoid craniectomy was performed to separate an enlarged and tortuous loop of the right anterior inferior cerebellar artery from the right facial nerve using a Teflon-felt sheet. The AVM was not excised. Postoperatively, she was completely free of hemifacial spasm.