The aim of the present retrospective study was to examine the expression of HHLA-2 in tumours of patients that underwent resection of pancreatic cancer or the pancreato-biliary subtype of ampullary cancer, and to study its biological relevance in these cancer types by relating its expression to baseline known clinicopathologic factors and outcome. This evidence concerns the gene HHLA2 and carcinoma of the ampulla of vater.