Two papillary and solid tumors of the pancreas are reported which differed in their clinical features, ultrastructure, and biologic behavior. Both tumors contained papillary and solid areas by light microscopy. One tumor followed the more usual indolent course. The second patient presented with a liver metastasis and died of progressive disease in a relatively short period of time. Neither neoplasm showed convincing immunohistochemical or ultrastructural evidence of endocrine differentiation, but the electron microscopic findings hinted that this tumor possesses at least latent endocrine properties.