The arachidonic acid metabolites prostaglandin E 2 (PGE 2 ) and leukotriene B 4 (LTB 4 ) are inflammatory mediators which are likely to be involved in the pathogenesis of periodontal disease. PGE 2 mediates vasodilatation, increases vascular permeability, enhances pain perception by bradykinin and histamine, alters connective tissue metabolism and enhances osteoclastic bone resorption. LTB 4 causes the accumulation of inflammatory cells in the inflamed sites, and degranulation of polymorphonuclear leukocytes.Objective: To measure gingival crevicular fluid (GCF) levels of PGE 2 , LTB 4 and periodontal health.Methods: The periodontal condition of 24 subjects was evaluated on the basis of plaque index, gingival index, probing depth, and attachment level. GCF samples were collected from one or two site(s) of each sextant per subject and the volume was measured using Periotron 6000. Samples were then assayed for PGE 2 and LTB 4 using a competitive enzyme immunoassay. Mean PGE 2 and LTB 4 levels were determined for each subject and group means compared.Results: Significant differences in the levels of PGE 2 and LTB 4 were found between patients with periodontitis, and non-periodontitis individuals (P<0.001). The PGE 2 /LTB 4 levels were positively correlated with the clinical parameters (P<0.01) and reduced markedly after phase 1 of the periodontal treatment (P<0.01). The total amount and concentration (ng ml - 1 ) of LTB 4 was positively correlated with the gingival index (P<0.01).Conclusions: These results indicate that the levels of PGE 2 correlated with the severity of the periodontal status, and the levels of LTB 4 correlated with gingival inflammation. Thus, our data suggest that the total amounts of PGE 2 /LTB 4 may be good indicators for periodontal inflammation.