It is important to obtain a good exposure of the root exit zone(REZ) of the facial nerve during microvascular decompression(MVD) for hemifacial spasm(HFS). For this purpose, authors dissected cerebellar cortical artery in addition to exposing the proximal portion of lower cranial nerves. During MVD for HFS, surgeons frequently meet a cerebellar cortical artery along the inferolateral aspect of cerebellar hemisphere. It is usually hemispheric branch of anterior inferior cerebellar artery(AICA) or posterior inferior cerebellar artery(PICA). It is reason that authors have dissected the outside arachnoid membrane attached pia mater of cerebellar cortical artery with a arachnoid knife or microscissor but preserve the inside arachnoid membrane attached dura mater. Microsurgical retractor is placed inferolaterally between cerebellar cortical artery and cerebellar hemisphere and elevated from the floor of the posterior fossa. The subarachnoid cisterns over the lower cranial nerves are opened with sharp dissector and wide operative fields and good exposure of REZ of facial nerve is obtained.