Nowadays, Chronic Apical Periodontitis closely associated with bacterial infections that result in alveolar bone resorption, still remains a pressing problem. One of the bacteria causing Apical Periodontitis is Porphyromonas gingivalis (Pg). Component of the Pg such as LPS has an ability to stimulate production of pro-inflammatory cytokines such as MMP8 that contributes to the degradation of periapical tissue. However, the role of MMP8 in periapical bone resorption remains unclear. The aim of this study was to analyze the role of MMP8 in periapical bone resorption. With Posttest only controlled group design, 21 of the three groups of male Rat Wistar were subjected. Chronic Apical Periodontitis was induced by exposure intrapulpa injection of 2 microliter PgLPS1435/1450 (1,0μg/ml) in aquades solution for three weeks on first upper molar. Group (P1) inducted LPS Pg, group (P2) got just LPS Pg solution and (Po) as control. After induction each subject was analyzed by MMP8 expression using immunohistochemistry assay. Data were analyzed using one-way Analysis of Variance (ANOVA) and Turkey's test statistics. The results showed expressions MMP8 in group P1 which were significantly different from group P2 p = 0,001*(p<0,05). Macrophage expressing MMP8 may play an important role in increasing the destructive mediators in chronic apical periodontitis.