The methods applied to the diagnosis of periodontal disease are changing. Historically, static clinical and radiographic parameters have formed the basis of the periodontal evaluation. As the limitations of these traditional procedures became clear, several new techniques have been proposed as diagnostic tests for periodontal disease. These tests are based on improved understanding of the pathogenesis of periodontal disease, and can be considered in three categories: assessment of physical changes in the periodontium, the bacterial infection, and the host response to the infection. Several technical questions must be addressed before these tests can be widely utilized. These specific concerns include such matters as the information available from the tests (e.g., Does the test provide a measure of disease severity or identify the site, region, or patient experiencing active disease?), the most appropriate test configurations, the statistical analysis of data from trials examining the accuracy of the tests, and selection of patients who would benefit from these procedures. Last, several important practical issues must be examined before these tests can be expected to gain widespread acceptance. These include familiarization of dental practitioners with the use of diagnostic tests and the medical laboratory, the role of regulatory agencies in determining the claims made by these tests, and the medical/dental insurance benefits provided for these services.