Immunohistochemical studies and DNA flow-cytometric investigations were performed in a case of solid-cystic tumour of the pancreas in a 35-year-old woman. All tumour cells were immunoreactive for the neuroendocrine cell markers chromogranin A and neuron-specific gamma-enolase. Moreover, about 10% of tumour cells were immunoreactive for insulin, while hypoglycaemia was absent. Few tumour cells (less than 1%) were immunoreactive for somatostatin, and no cells were found to be immunoreactive for pancreatic polypeptide or glucagon. No immunoreactivity was present for duct cell marker carcino-embryonic antigen and only individual cells were reactive for alpha 1-antitrypsin. Nuclear DNA content of the tumour cells was diploid and the proliferative activity was low. In confirmation of some reports on neuroendocrine markers in solid-cystic tumour of the pancreas, our findings support the theory that the lesion is a hormonally inactive neuroendocrine pancreatic tumour.