Peripheral T-cell lymphomas encompass lymphomas with a variety of histologic appearances and clinical patterns. In otolaryngological fields, it has been suggested that almost all of the histologic features described under the name of ""polymorphic reticulosis"", ""lethal midline granuloma"" or ""midline malignant reticulosis"" can be included in those generally described T-cell lymphomas of peripheral T-cell origin. Recently the authors experienced 2 cases of peripheral T-cell lymphoma from nose and tonsil. We have analysed DNA contents of these tumors using flow cytometry and studied IL-6 expression and lymphocyte subset by immunohistochemistry using Avidin biotin complex method. Immunohistochemial results showed that strong immuno-reactive staining for UCHL-1(T-cell marker) was seen in atypical lymghocytes. Both cases showed diploidy pattern with moderate increase of proliferation index in flow cytometry. In study of IL-6 expression, nasal turbinate mass, which showed more atypical cells infiltration, demonstrated no increase of IL-6 expression but previous biopsy diagnosed as nonspecific inflammation showed relatively strong immunoreactivity for IL-6. The tonsillar mass revealed strong immunoreactive cells for IL-6. The rarity of these disease makes prospective or large retrospective studies difficult. Nevertheless further studies using monoclonal antibody B & T-cell immunotyping techniques or other methods in individual cases should provide further insights into the etiology and pathogenesis of this intriguing diseases.