Periodontitis represents a chronic bacterial infection that induces immuno-inflammatory conditions affecting gingiva and tooth-supporting tissues. The role of some biological mediators in periodontal disease was widely investigated, especially that of MMP-8 and MMP-9. Recently, MMP-2 was also considered to be an appropriate therapeutic target for prevention of periodontal disease progression. However, effects of the combination of metronidazole with amoxicillin or spiramycin on the release and activation of MMP-2 and the balance MMP-2÷TIMP-2 were rarely studied. This study was designed to assess the influence of two combinations of antibiotics used for treatment of periodontitis on the balance MMP-2÷TIMP-2. Gingival samples obtained from patients with no pharmacological treated chronic periodontitis and those receiving either the association between amoxicillin-metronidazole and spyramicin-metronidazole were processed for paraffin embedding and then used to perform immunohistochemical reactions in order to detect MMP-2 and TIMP-2. All subjects were evaluated clinically and radiographic at the first visit and after treatment completed, the Loe & Silnees gingival index at six sites per tooth for the whole mouth being recorded. Statistical analysis was performed using non-parametrical techniques. Gingiva samples from untreated chronic periodontitis patients revealed a diffuse positive reaction for MMP-2 in the epithelium and also in fibroblasts and macrophages from the lamina propria. For gingiva samples from patients treated with antibiotics, MMP-2 positive reaction was restricted to deep epithelial layers and few cells of the connective tissue. No significant difference was observed for TIMP-2 expression. The clinical indexes were in accordance with immunohistochemical results. After treatment, gingival index values were significantly lower then before (p<0.001) in both groups treated with antibiotics.The two combinations of antibiotics tested in our study seem to have a dual ability to reduce inflammation as well as to inhibit MMP-2 activity.