Among 121 cases of primary gastric malignant lymphoma from 1962 to 1994 at the National Cancer Center Hospital, Tokyo, we found four cases (three males and one female) of adenocarcinoma coexisting in the stomach. The incidence of gastric malignant lymphoma together with gastric adenocarcinoma was 3.3%, suggesting that patients with lymphoma may have an increased incidence of gastric adenocarcinoma. A review of the Japanese literature revealed an additional 62 patients who developed coexisting gastric malignant lymphoma and adenocarcinoma. In the total series of 66 patients whose age and sex were recorded, there were 48 males with a mean age of 63.8 years and 18 females with a mean age of 58.6 years. Most adenocarcinomas were macroscopically early (76%) and of histologically differentiated type (75%). Conversely, 71% of lymphomas were of the advanced type macroscopically. The correct preoperative diagnoses were made in only 27% (16/59) of cases, when both tumors were located independently.