The authors describe in the presented paper the interesting development of a primary non-Hod- gkin lymphoma of the stomach and small intestine which was treated for eight months as a gas- tric ulcer and even operated on account of perforation of a prepyloric ulcer. During repeated gastroscopic examinations always the diagnosis of peptic ulceration was made, once Helicobacter pylori was positive. Because of persisting complaints and the endoscopic finding the patient was indicated for surgery which revealed a large ulcer in the prepyloric area penetrating into the ligamentum hepatoduodenale and the head of the pancreas. As a secondary finding stenotizing jejunal infiltration was present. Histological examination of the resected portion of the stomach and jejunum revealed diffuse non-Hodgkin malignant lymphoma series B. At the medical clinic the patient had four courses of chemotherapy. At present, i.e. 12 months after resection, he feels well and the paraclinical examinations are not pathological.

        Key words: malignant non-Hodgkin gastric lymphoma – surgery – chemotherapy