OBJECTIVE To look for Epstein-Barr virus (EBV) in a series of gastric cancers of common and rare histological types. METHODS Formalin sections from 19 cases of gastric carcinomas of different types were studied using in situ hybridisation with fluorescein conjugated EBER oligonucleotides and the avidin-biotin complex immunoperoxidase technique, using the monoclonal antibody Dako-EBV CS 1-4. RESULTS The only positive tumour was a lymphoepithelioma-like gastric carcinoma. The remaining 18 cases, which included 11 consecutive cases of usual adenocarcinomas, three early gastric cancers, two adenosquamous carcinomas, and a case each of signet ring carcinoma and neuroepithelioma, were all negative. However, scattered EBV positive cells were seen in the normal gastric or duodenal mucosa bordering the tumours in seven out of 11 cases. CONCLUSIONS Lymphoepithelioma-like gastric carcinoma seems to be the main, if not the only, EBV positive gastric cancer. The presence of EBV positive normal gastric and duodenal cells suggests that these cells may act as a reservoir for the virus in some people--a possibility that deserves wider investigation.