The results of a retrospective study on patients with lymphomata and pseudolymphomata are presented. The interpretation of histological findings may be difficult. This is demonstrated by two cases. In both of them the histological structures in the biopsies were regarded as benign. The course of the disease however, demonstrated malignancy. The term "pseudotumour" of the orbita ought to be used carefully. The treatment and the prognosis of malignant lymphomata demand a classification, reflecting the biological behaviour of the lymphomata. Such classification was elaborated by an International group and is known as the Kiel classification. It should be applied in lymphomata of the orbital region, too. The use of an uniform classification of the malignant lymphomata is essential for all disciplines, involved in the diagnosis and treatment of the neoplasms.