Twenty-two cases of primary lymphoma of the gastrointestinal tract are reported. These have been seen over the past 16 years and consist of seven gastric, 13 small bowel and two caecal lesions. This number represents 0.07% of the barium examinations of the stomach and small bowel, conducted over this period. All the cases were examined by the conventional barium meal or barium meal and follow-through examinations using non-flocculable barium. All the lymphomas were verified by histological examination. The cases are analysed as to clinical and radiological presentation, and the clinical and radiological diagnostic scores are assessed. There was a very poor diagnostic score on clinical grounds alone; a high diagnostic score for radiological examination of the stomach of 71%, contrasted with a low radiological score of 26% for the small bowel. The radiological features of lymphoma in the stomach and small bowel are described and the differential diagnosis discussed. To improve the diagnostic score on radiological examination, an awareness of gastrointestinal lymphoma is essential, as is a knowledge of the possible radiological changes. The barium examination should carefully search for these changes where lymphoma is clinically possible.