Due to the fatal prognosis of pancreatic carcinoma, great efforts have been made to investigate precursor lesions of invasive neoplasia during the last few years. Pancreatic intraepithelial neoplasias (PanIN) have been recognized as precursor lesions of ductal adenocarcinoma, and are classified into different grades from PanIN-1A, -1B, -2, to -3. Molecular analyses have helped to define a progression model for pancreatic neoplasia. The most important step seems to be the occurrence of a PanIN-3 lesion defining a high risk of malignant transformation. As in PanINs, different types of intraductal papillary-mucinous neoplasms (IPMN) can be discriminated ranging from benign to invasive lesions. Becoming invasive, some of these tumors appear as ductal adenocarcinoma, others as colloid carcinoma with a much better prognosis. In this review, the characteristics of these two precursor lesions and their genetic alterations are summarized.