Twenty-two cases of lymphoid tumours of the stomach were reviewed by application of the Kiel classification for non-Hodgkin's malignant lymphomas. Four cases of pseudolymphomas were found, one of which had been previously misdiagnosed as malignant lymphoma. The remaining cases were all malignant tumours with B-cell lymphoma features. These were divided into seven low grade lymphomas (three immunocytomas and four centroblastic/centrocytic) and II high grade lymphomas (six centroblastic and five immunoblastic lymphomas). No cases of Hodgkin's disease or lymphoblastic lymphoma were observed. The Kiel nomenclature was not only easy to apply, but also helped to differentiate pseudolymphoma from malignant lymphoma. Both the pseudolymphomas and the malignant lymphomas were consistently associated with follicular gastritis. This lesion, while intrinsically non specific, was sometimes accompanied by suggestions of transition between itself and the lymphoma, a fact which at least raises the possibility of a transformation of the former into the latter.