Periodontal disease research has been focused on understanding the immunopathologic mechanisms which may operate in the development and maintenance of peiodontal inflammatory changes. Immunologic and inflammatory responses may relate to the etiology and pathogenesis of periodontal disease. In order to research immunopathology of periodontal disease, previous investigators have spent much time on the distribution of lymphocyte subpopulations and NK cells but they have spent less time on the changes of those cells to the periodontal disease severity. The purpose of study was performed to investigate the changes of the distribution of T lymphocytes, B lymphocytes, T lymphocyte subsets, and Natural Killer cells in the gingival epithelium and connective tissue of the periodontal disease with the various clinical parameters including Gingival Index, Sulcular Bleeding Index, and pocket depth. Gingival tissues were obtained from 25 patients with different severity of periodontal disease. Serial cryostat sections displaying a cross section of gingiva were labelled with monoclonal antibody for pan T cells, T cytotoxic^{pressor cells, T helper}inducer cells, pan B cells, and NK cells were develped using an avidin-biotin-peroxidase system. Lymphocyte populations were enumerated in repeatable fields from gingival section. 1. T cells were more increased at grade 1 and 3 than at grade 0 of gingival index (p<0.05). Helper T cells and NK cells were significantly increased at grade 1, 2, 3 than at grade 0(p<0.05). 2. T cells were more decreased at grade 3 and 4 than at grade 1 of sulcular bleeding index (p<0.01, p<0.05). Especially, Natural Killer cells were significantly increased at grade 1, 2, 3, 4 than at grade 0 (p<0.05, p<0.001). 3. The ratios of helper T^{pressor T cells were more decreased at grade 4 than at grade 0 and at grade 4 than at grade 2 of sulcular bleeding index (p<0.05, p<0.05). 4. Helper T cells were significantly decreased at grade II and III than at grade I, however the Natural Killer cells showed a increasing tendency with the increase of the pocket depth, there were no significant differences between each grade of pocket depth. 5. The ratios of helper T}suppressor T cells were tended to be decreased with the increase of the pocket depth, there were no significant differences between each grades of pocket depth. There was a very weak change in the distribution of T lymphocytes, B lymphocytes, T lymphocyte subsets, and Natural Killer cells in the gingival epithelium and connective tissue of the periodontal lesion with the various clinical parameters including gingial index, sulcular bleeding index, and pocket depth. But, the number of T lymphocytes and Natural Killer cells were significantly changed in gingival index and sulcular bleeding index.