This study sponsored by the Lymphoreticular Study Group of the Korean Society of Pathologists was carried out to provide nationwide data about the histopathologic-immunophenotypic features of malignant lymphomas in Korea. Two hundred and ninety Non-Hodgkin's lymphoma (NHL) among 312 malignant lymphomas collected from three representative areas in Korea were histologically reclassified. Two hundred and fifty three cases were immunohistochemically studied. T-cell lymphoma comprised 35.2% of NHL in this study and showed a quite comparable incidence to that of Japan and China, but it was much higher than in Western countries. A very low prevalence rate of the follicular variety (4.0%) and a higher propensity of primary extranodal involvement (60%) are additional characteristics of NHL in Korea. The most common histologic subtype of B cell lymphoma was diffuse large cell type, whereas the most common subtype of T cell lymphoma was diffuse mixed small and large cell type.