Background: Matrix metalloproteinases (MMPs) stimulate alveolar bone loss in chronic periodontitis. Objective: To evaluate the salivary and gingival crevicular fluid (GCF) levels of MMP-8 in patients with moderate to severe chronic periodontitis. Methods: 42 participants were divided into two groups: a case group (21 patients with generalized moderate to severe chronic periodontitis) and a control group (21 healthy periodontal subjects). GCF and saliva samples were obtained from both groups. Salivary and GCF MMP-8 levels of each subject were detected using the ELISA method. Results: Mean±SD values of salivary MMP-8 levels of the control and case groups were 1.52 ± 0.65 ng/ml and 6.06 ± 1.18 ng/ml, respectively, and statistically significant difference was observed (p=0.0001). Also, mean±SD values of GCF MMP-8 levels of the control and case groups were 0.87 ± 0.26 ng/ml and 2.92 ± 0.64 ng/ml, respectively; which was statistically significant (p=0.0001). Conclusion: Our results demonstrate an increased concentration of salivary and GCF levels of MMP-8 in the patient group.