This placebo-controlled double-blind study was aimed at determining the effects of mouthrinses containing amine fluoride/stannous fluoride (AmF/SnF2), triclosan and acetylsalicylic acid (ASA) on the levels of prostaglandin E2 (PGE2); leukotriene B4 (LTB4) and thromboxane B2 (TxB2) in gingival crevicular fluid (GCF) during experimental gingivitis and subsequent rinsing phase. 44 subjects participated in the study. To establish healthy gingival conditions, all subjects underwent a 3-week period of professional tooth cleaning and oral hygiene instruction. Plaque and gingivitis assessments, microbial sampling and gingival crevicular fluid assessment were performed at baseline. At the second examination healthy conditions were recorded. For the next 14 days, the subjects were asked to abstain from any form of oral hygiene (experimental gingivitis phase). The 3rd and 4th examinations were performed 7 and 14 days after the 2nd examination and was followed by random assignment of mouthrinses containing either AmF/SnF2, triclosan, ASA or placebo. These mouthrinses were used for 22 days with no additional oral hygiene measures (rinsing phase). During this period the 5th and 6th examinations were performed at 25 and 36 days after the 2nd examination. Immunological evaluation of the gingival crevicular fluid (GCF) was done by enzyme immunoassay with respect to PGE2, LTB4 and TxB2. Statistical analysis was based on the Kruskal-Wallis test and the Wilcoxon-Mann-Whitney test. The findings revealed no significant change in TxB2 levels during the experimental gingivitis phase for all subjects, while the PGE2 levels showed a significant increase between the 2nd and 4th examinations. Combined data from all subjects revealed significant reductions in PGE2 and LTB4 during the rinsing phase between the 4th and 5th examinations, while TxB2 levels were increased during the rinsing phase. However, no statistically significant inter-group differences were observed in reducing the GCF inflammatory mediators between the rinsing solutions after a 22 days rinsing period.