The aim of the present study was to investigate the use of a radial artery graft (RAG) for bypass of the proximal superficial temporal artery (STA) to proximal posterior cerebral artery (PCA) by posterior oblique transzygomatic subtemporal approach as an alternative to the external carotid artery (ECA) to PCA anastomosis. We conducted an anatomical and technical study at a university hospital. Five adult cadaveric specimens were dissected. A preauricular vertical skin incision was used. The trunk of STA was identified. A 30 degrees oblique posterior zygomatic arch osteotomy and microcraniotomy was performed. The dura of the middle cranial fossa was then opened. The temporal lobe was retracted, the interpeduncular and ambient cisterns were opened, and the P2 segment of the PCA was exposed. The proximal side of the RAG was anastomosed with the proximal STA and the distal side was anastomosed with the P2 segment. The mean caliber of the proximal STA was 2.25 +/- 0.35 mm. The mean diameter of the P-2 was 2.2 +/- 0.2 mm. The average length of the RAG was 56 +/- Ce3.2 mm. The mean caliber of the proximal and the distal sides of the graft was 2.5 +/- 0.25 mm and 2.3 +/- Ce0.15 mm, respectively. Because the proximal STA to proximal PCA bypass uses a short RAG and their calibers are over 2 mm, this bypass technique can provide a sufficient blood flow and may be a reasonable alternative over ECA to PCA bypass using long grafts.