The immunohistochemical expression of chromogranin A (CGA) was investigated in 60 normal mucosas, 95 primary tumours and 38 metastatic lymph nodes. CGA was expressed in 100% of the normal mucosas, 61% of the primary tumours that were restricted within the submucosal layer, 21% of the primary tumours that invaded beyond the submucosal layer, and 11% of the metastatic lymph nodes. The 5-year survival rates in patients with negative and positive expression of CGA in primary tumours were 60.4% and 74.6%, respectively. These results indicate that endocrine cells occupy an integral part of gastric adenocarcinoma with regard to tumour progression.