Since periodontal infections are suggested as risk factors for the development of cardiovascular diseases, the present study was performed to evaluate the T cell immune responses specific to Porphylomonas gingivalis(P. gingivalis) heat shock protein(hsp) 60 and T-cell and B-cell epitope specificities for P. gingivalis hsp60 in atherosclerosis. Anti-P. gingivalis IgG antibody titers were elevated in all patients. We could establish P. gingivalis hsp-specific T cell lines from the atheroma lesions, a mixture of CD4⁺ and CD8⁺ cells producing the cytokines characteristic of both Th1 and Th2 subsets. of 108 overlapping synthetic peptides spanning whole P. gingivalis hsp60 molecule, ten peptides with common epitopes specificities for both T-cell and B-cell were identified. it was concluded that P. gingivalis hsp60 might be involved in the immunoregulatory process of atherosclerotic diseases with epitope specificities.