Abstract: AIM: To explore the invasion of porphyromonas gingivalis (P.g), a periodontal pathogen, in the pathogenesis of coronary heart disease. METHODS: Four different strains of P.g were tested for adhesion and invasion of human gingival epithelial cells (HGEC), human umbilical vein endothelial cells (HUVEC) and human coronary artery endothelial cells (HCAEC). The strains were tested for the ability to attach to and invade HGEC, HUVEC and HCAEC using a standard antibiotic protection assay. RESULTS: Data indicated that the invasion efficiency of P.g was different among the different strains. The same strain showed a different ability to adhere to and invade different types of cells. The efficiency of P.g adhesion and invasion of HGEC and HCAEC was higher than HUVEC. CONCLUSION: P.g strains have a stronger ability to adhere to and invade both HGEC and HCAEC.