In two cases of solid and papillary neoplasm of the pancreas (SPN), positive staining for argyrophil granules, chromogranin-A, neuron-specific enolase, chymotrypsin, alpha 1-antitrypsin, vimentin, cytokeratin, and estrogen receptors was present. Ultrastructurally, neurosecretory as well as zymogenlike granules were demonstrated. Measurements of mean nuclear volume and volume-corrected mitotic index discriminated between SPN and well-differentiated ductal adenocarcinoma of the pancreas, with notably lower values being seen in SPN. Silver-stained nucleolar organizer region counts showed wide overlaps. The results suggest that SPN is a tumor with mixed endocrine and exocrine features. Its low malignant potential compared to ductal adenocarcinoma is reflected in the mean nuclear volume and volume-corrected mitotic index. The presence of estrogen receptors may prove therapeutically useful.