Primary gastric lymphoma accounts for 2.5% of all malignant gastric neoplasms. The clinical, macroscopic, and radiological appearances frequently resemble those of other gastric lesions, notably carcinoma. However, the prognosis of lymphoma is much better and accurate diagnosis is therefore important. The prognosis of secondary gastric lymphoma is less good but its accurate recognition is still important. Conventional radiology is a key investigation and the radiological appearances have been reviewed in 18 patients with a histological diagnosis of lymphoma. 5 of these were already known to have lymphoma elsewhere. The radiological appearances were similar whether or not there was lymphoma elsewhere. There is no single accurate pattern of recognition but the following features occurred often enough to be useful pointers: (a) Distensible stomach in the presence of a mass. (b) Mucosal hypertrophy in the presence of a mass. (c) Mucosal hypertrophy associated with large gastric ulcer or multiple gastric ulcers. (d) Contiguous spread of abnormality into the duodenal cap. (e) Duodenal ulceration associated with gastric mass. (f) The youth of the patient. The reported incidence of primary lymphoma of the stomach is 2.5% of all malignant gastric neoplasms ( Welborn et al., 1965 ). Similarly about 2.5% of lymphomas present with a primary lesion in the stomach ( Bush and Ash, 1969 ). Its very rarity leads to difficulty in recognition and at laparotomy it may resemble an inoperable carcinoma ( Salmela, 1968 ). However, the prognosis of lymphomas is much better than that of carcinoma ( Jenkinson et al., 1954 , Jordan et al, 1955 ) even when regional lymph nodes are involved ( Friedman, 1959 ), and the treatment of choice is resection followed by radiotherapy ( Friedman, 1959 ). Therefore accurate pre-operative diagnosis is important. Secondary lymphoma of the stomach occurs more often than the primary form ( McNeer and Berg, 1959 ) but is still uncommon, and occurs in up to 3.5% of patients known to have lymphoma ( Rosenberg et al, 1961 : Block, 1967 ). The prognosis is not as good as in the primary form ( Snoddy, 1952 ), but early recognition of gastric involvement is still important so that appropriate local treatment can be undertaken ( Burnett and Herbert, 1956 ). The diagnosis of both forms of the disease has proved difficult from clinical features ( Sherrick et al., 1965 ) and from radiological studies ( Jenkinson et al., 1954 ; Jordan et al., 1955 ). The most optimistic estimate of a 50% success rate was obtained after combined clinical, radiological and gastroscopic examination ( Palmer, 1950 ). Radiological studies remain the most important investigation ( Ochsner and Ochsner, 1955 ), but have proved disappointing. 18 consecutive cases of proven lymphoma of the stomach have been reviewed to seek a reliable pattern of recognition.