The precancerous conditions associated with pancreatic ductal carcinoma include preneoplastic duct changes and benign-looking tumors that give rise to ductal carcinomas. Among the duct changes that are discussed as precancerous lesions are hyperplastic and metaplastic lesions, which were recently classified as pancreatic intraepithelial neoplasia types 1A, 1B, 2, and 3. This new system is compared with the older terminology. Recent molecular findings concerning the most frequent genetic alterations in manifest carcinomas support the new classification system. The relative frequency of duct lesions in the nonneoplastic pancreas and their association with chronic pancreatitis and ductal carcinoma are discussed. Finally, the pancreatic exocrine tumors that may give rise to ductal carcinomas are presented.