The aim of this study is to contribute our experience to the knowledge of the anatomic variations of the hepatic arterial supply. The surgical anatomy of the extrahepatic arterial vascularization was investigated prospectively in 1,081 donor cadaveric livers, transplanted at La Fe University Hospital from January 1991 to August 2004. The vascular anatomy of the hepatic grafts was classified according to Michels description (Am J Surg 1966;112:337-347) plus 2 variations. Anatomical variants of the classical pattern were detected in 30% of the livers (n ϭ 320). The most common variant was a replaced left artery arising from the left gastric artery (9.7%) followed by a replaced right hepatic artery arising from the superior mesenteric artery (7.8%). In conclusion, the information about the different hepatic arterial patterns can help in reducing the risks of iatrogenic complications, which in turn may result in better outcomes not only following surgical interventions but also in the context of radiological treatments. Knowledge of hepatic arterial vascularization has a significant relevance for the daily practice of a wide range of practitioners including not only surgeons specialized in the hepato-biliary-pancreatic area, but also general surgeons and radiologists, mainly those who are dedicated to interventional radiologic treatments.In the last few years, substantial improvements have been achieved in the surgical and/or radiological treatment of benign and malignant liver, pancreatic, and biliary diseases. With laparoscopic surgery the need has arisen for exact descriptions of the hepatic vascularization to avoid iatrogenic vascular lesions.In the setting of liver transplantation, the most effective approach to reduce the dropout rate on the waiting lists is to expand the number of available livers. Several strategies including living donors and split livers have been developed for this purpose. These are extremely complex techniques in which the exact knowledge of the arterial anatomy is a required step to plan the best resection as well as to minimize the risks of morbidity.The patterns of hepatic arterial supply are not constant. The usual anatomy of the hepatic arterial vascularization is a common hepatic artery arising from the celiac axis, accounting for 25 to 75% of the cases. 1 In the variant patterns, the hepatic lobes receive arterial flow through branches coming from the superior mesenteric artery, left gastric artery, or, rarely, from other arterial trunks. 2 Since Michels 3 published his first report, several studies have reported not only common and rare hepatic artery variants, but also different classifications. These studies are based on angiographic data and autopsy dissections, and mainly derive from surgery and transplantation literature. [4][5][6][7][8][9][10][11][12][13][14] The large sample size of transplanted livers is one of the major interests of this study. Indeed, harvested livers offer an excellent opportunity to describe, in situ, the anatomic variants of the arteries since all e...