A computer-assisted medline search was conducted to find the relevant articles concerning the periodontal disease markers in gingival crevicular fluid (GCF) and saliva published during the 10-year period from 1993 to July 2003. This review suggests that certain diagnostic uses of saliva and GCF show promise. Although both fluids have been used to evaluate the risk for an individual to develop periodontal disease and to monitor of the host response to periodontal therapy, GCF has the chance of being closely approximated to the periodontal tissues where periodontal disease begins. The enzymes contributed to extracellular matrix (ECM) molecules and non-ECM molecules degradation and markers for polymorphonuclear leukocytes (PMN) activity and influx into the gingival tissue seem to provide valuable information regarding the periodontal disease diagnosis and prognosis. There is also an increasing evidence implicating reactive oxygen species and nitric oxide pathway in the pathogenesis of periodontal diseases. Although promising results have been achieved with the assays evaluating the markers in assessment of periodontal disease status, up to now, none of these tests are used routinely. Further, one commercially available genetic test has been reported to have the potential to be used to predict the periodontal disease, but there are controversial reports on this genetic susceptibility test. (C) 2004 Elsevier B.V. All rights reserved.