Nine acinar cell carcinomas of the pancreas, 2 pancreatoblastomas, 16 solid-cystic (papillary-cystic) tumors, and 20 ductal adenocarcinomas were immunocytochemically investigated using antisera against four pancreatic enzymes (alpha-amylase, lipase, trypsinogen, chymotrypsinogen), four pancreatic hormones, neuron specific enolase (NSE), alpha-1-antitrypsin (AAT), carcinoembryonic antigen (CEA), and CA 19-9. Lipase, trypsinogen, and chymotrypsinogen, but no alpha-amylase were detected in all acinar cell carcinomas and pancreatoblastomas. In contrast, solid-cystic tumors (SCT) were negative for pancreatic enzymes but 2 of 16 stained with NSE. No neuroendocrine granules or pancreatic hormones could be demonstrated. AAT was found in all tumors except ductal adenocarcinomas, which stained with CEA and CA 19-9. The study established pancreatic enzymes (except alpha-amylase) as immunocytochemical markers for acinar cell carcinomas and pancreatoblastomas. There is as yet no marker specific for SCT, which would elucidate the obscure histogenetic origin and phenotypic differentiation of these tumors.