The study aims to identify and quantify Porphyromonas gingivalis in chronic and aggressive periodontitis patients in comparing to healthy subjects by qPGR. The comparison were in both diseased sites of chronic periodontitis patients (P. gingivalis 25.10 + and - 4.68) Cycle threshold (Ct) and healthy subjects (P. gingivalis 33.93 + and - 3.17 Ct) respectively (p 0.05). The comparison were in both diseased sites of aggressive periodontitis patients (P. gingivplis 22,89 + and - 4,63 Ct) and healthy subjects (P. gingivalis 34.38 + and - 2.96 Ct) respectively (p 0.01). In conclusion, porphyromonas, gingivalis was very common bacteria in both chronic, aggressive periodontitis patients (100 percent) and there was a significant difference of Porphyromonas gingivalis quantity in comparison with healthy subjects (p 0.05).