On the basis of morphoimmunological correlates certain criteria have been elaborated helpful in diagnosis of non-Hodgkin's malignant lymphomas (NML) of both B- and T-cell origin, and this was reflected in the modified Kiel's classification. The group of T-cell NML has considerably increased. T-cell origin of Lennert's lymphoma and angioimmunoblastic lymphadenopathy has been proven. Morphological substrate of NML from peripheral T-lymphocytes became more precise. The tumours, depending on the predominant cells, are subdivided into small cell (T-zones and pleomorphic lymphoma of small cells), mixed cell (pleomorphic lymphoma of medium-size and large cells) and large cell lymphoma (immunoblastic and large cell anaplastic Ki-I+). Criticism of T-NML systematization is due to the lack of definite cytological criteria because of the extreme morphological heterogeneity of peripheral T-lymphocytes and different interpretation of the clinical course of the established morphological variants. Among B-cell lymphomas the problem of the so-called intermediate lymphocytic lymphoma (ILL) and its variety--a mantle-zone lymphoma as well as monocytoid B-cell lymphoma is discussed in the literature. It is established in immunological testing that the cells of ILL possess a phenotype of cells of the primary follicles and those of the mantle-zone of the secondary follicles while the cells of the monocytoid B-cell NML have a peculiar unique phenotype similar to that of cells in the marginal zone of the spleen follicles.