Epstein-Barr virus DNA was detected by polymerase chain reaction in a paraffin-embedded block of an undifferentiated lymphoepithelial gastric carcinoma but was absent in a poorly differentiated gastric adenocarcinoma which also had pronounced lymphoid stroma. This is the first report, to our knowledge, of a lymphoepithelial carcinoma of the stomach. The association with Epstein-Barr virus and the distinctive histologic appearance justify the separate classification of undifferentiated lymphoepithelial carcinomas of the stomach similar to those of the nasopharynx from adenocarcinomas with lymphoid stroma.