This study reviewed 65 cases of polymorphic reticulosis (PR) with respect to clinical and histopathologic bases, and immunohistochemical studies were done using MT1 and UCHL as T-cell markers, MB2 as a B-cell marker and alpha-1-antichymotrypsin as a histiocytic marker. The results obtained were as follows: 1. The male to female ratio was 2.4:1 and the mean age of patients was 44.5 years. The sites involved primarily were the nasal cavity, tonsil and pharynx and about one-fourth of the total cases showed extensive involvement of two anatomical sites at initial presentation. 2. Almost all cases showed characteristic histologic features similar to those of peripheral T-cell lymphoma and showed positive reaction to the T-cell marker. The above immunohistochemical findings suggest strongly that quite a significant portion of PR is in fact T-cell lymphoma.