The purposes of this study were to evaluate the prognostic significance of Glut-1 expression in patients with pancreatic ductal adenocarcinoma, and to analyse its expression in pancreatic intraepithelial neoplasias (PanIN) and non invasive intraductal papillary mucinous neoplasms (IPMN). Glut-1 expression was studied by immunohistochemistry in 60 pancreatic ductal adenocarcinomas and scored on a 4-point scale (1: <25%; 2: 25-50%; 3: 50-75%; 4: >75%). Relationships between Glut-1 score, histological grade and MIB-1 score were evaluated by the Spearman rank correlation test. Significant correlations were found between Glut-1 expression and histological grade (P<0.001) and MIB-1 score (P<0.01). Significant prognostic factors by univariate analysis were stage (P<0.0001), histological grade (P<0.001) and Glut-1 expression (P<0.005). Independent prognostic factors after multivariate analysis were stage (P<0.001) and Glut-1 expression (P<0.05), stratified as <50% and >50%. The correlation of Glut-1 score with histological grade and MIB-1 score indicated a higher glucose uptake in poorly differentiated and highly proliferative pancreatic cancer cells. Glut-1 immunohistochemical expression provides a useful prognostic factor in pancreatic ductal adenocarcinoma. Glut-1 expression was not found in PanINs 1 but in 27.8% and 43.8% of PanINs 2 and 3, and was not found in IPMNs with low- and moderate-grade dysplasia but in 60% of IPMNs with high-grade dysplasia, indicating Glut-1 involvement in a relatively early phase of pancreatic carcinogenesis.