Over 80% of adenocarcinomas of the pancreas originate from duct cells, which are the major source of mucins in the pancreas. Pathological conditions produce changes in the composition and structure of the oligosaccharides of colonic and pancreatic mucins, and it has been suggested that mucins may have a role in the detection of pancreatic cancer. Mucins are now the targets of a number of immunodiagnostic assays for cancer, and their possible use in therapy is being studied. This review describes the structure, biosynthesis, and release of mucins, as well as some of their therapeutic applications. The MUC1 type of mucin is emphasized because it is the main type present in both normal and malignant pancreas and because it is associated with several of the serological pancreatic cancer carbohydrate markers, including CA19-9.