The Objective This study aimed to analyze active matrix metalloproteinase (aMMP-8) levels in gingival crevicular fluid (GCF), saliva and serum in the context of new criteria of gingivitis and stage 3 grade C periodontitis. The Background Periodontal disease is an inflammatory process that can result in tooth loss and also is considered a modifying factor for systemic health. Matrix metalloproteinase (MMP)-8 is the major collagenase of periodontal tissue breakdown. Methods Totally 83 systemically healthy and non-smoker individuals consisting of 23 periodontally healthy, 20 gingivitis and 40 stage 3 periodontitis, were recruited to the study. Clinical periodontal examinations of probing depth (PD), clinical attachment loss (CAL), gingival index (GI), plaque index (PI) and bleeding on probing (BOP) were recorded; and GCF, saliva and serum samples were obtained. aMMP-8 was measured by immunofluorometric assay (IFMA). Results GCF and serum aMMP-8 levels were significantly increased in periodontitis and gingivitis compared to healthy ones (P < .001), whereas gingivitis and periodontitis patients showed similar levels of aMMP-8 in GCF and serum (P > .05). Saliva levels of aMMP-8 were higher in periodontitis patients than both gingivitis and healthy individuals (P < .001). There was no significant difference in salivary aMMP-8 levels between gingivitis group and healthy controls (P > .05). Conclusion These findings support the involvement of aMMP-8 in periodontal diseases and suggest that its local and systemic levels can reflect stage 3 grade C periodontitis. Moreover, aMMP-8 in GCF and serum seems to have a potential to differentiate between gingivitis and periodontal health.