Objective: To elucidate the aetiology of periodontitis, this study focused on the adenosine receptor (AR) expression profiles (A1AR, A2AAR, A2BAR and A3AR) in periodontal diseased tissues. Methods: Adenosine receptor gene expression levels in human gingiva from 15 patients with healthy gingival tissues (control group) and 15 patients who exhibited severe chronic periodontitis (test group) were measured using quantitative reverse transcription-polymerase chain reaction (RT-PCR). Results: The mRNA expression pattern changed in human chronic periodontitis: the A1AR decreased 20%, A2AAR increased 2.5-fold, A2BAR increased 3.7-fold and A3AR decreased 70% as compared with that of healthy gingiva. Conclusion: Inflammation of the gingival tissue is associated with (1) an unchanged expression of A1AR, (2) an increased expression of A2AAR and A2BAR, and (3) a decreased expression of A3AR. Logistic regression analysis indicated that the change in the expression patterns can be used to diagnose/predict periodontitis. This finding indicates that the adenosine receptor expression profile is changed in periodontitis with the potential for future clinical application. Keywords: adenosine receptor, chronic periodontitis, gene expression profiling, inflammation mediator