BACKGROUND Root exit zone (REZ) compression by a fusiform vertebral artery (VA) aneurysm is a rare cause of hemifacial spasm (HFS). We report a case of successful microvascular decompression (MVD) for the treatment of HFS caused by a fusiform VA aneurysm. We also review the relevant literature and demonstrate the effectiveness of surgical treatment. METHODS A 64-year-old man presented with a 2-year and 4-month history of progressive involuntary facial twitching on the right side. Radiological examination revealed a fusiform right VA aneurysm. The REZ that was compressed by the aneurysm and the underlying anterior inferior cerebellar artery (AICA) was surgically decompressed by transposing the VA and AICA and wrapping the aneurysm. Immediately post-operation, the patient's symptoms disappeared. For 7 years and 4 months postoperatively, there was no symptom recurrence or increase in aneurysm size. CONCLUSIONS MVD is an effective treatment for HFS caused by a fusiform VA aneurysm because symptoms are likely to improve immediately after treatment.