Gastrin may play a role in gastric carcinogenesis, as indicated by an increased frequency of gastric carcinomas in patients with pernicious anaemia and the fact some human gastric cancer cell lines carry the gastrin receptor. Recently, it has been shown that the acid-stimulatory effect of gastrin may be solely mediated by histamine release from the enterochromaffin-like (ECL) cell, on which gastrin has a specific trophic effect. We therefore found it of interest to examine human gastric carcinomas for the presence of ECL tumour cells by using silver staining and chromogranin immunohistochemistry. We found evidence of ECL cell-derived tumour cells in 40% of the diffuse gastric carcinomas but no such tumour cells in the intestinal type of gastric carcinoma. This may suggest that diffuse gastric carcinomas, like malignant gastric tumours of the mastomys, are in fact malignant ECLomas.