When periodontal disease started to be considered a bacterial infection mainly mediated by subgingival plaque, the basic problem faced by periodontists was the identification and/or quantification of periodontopathogenic bacteria. However, clinical methods continue to be of great value for the diagnosis of periodontal disease. In the present study we show a significant correlation between an index widely used in clinical practice, the Gingival Index of Löe (1967), based on the presence or absence of bleeding on probing, and the methodology of the BANA test for the detection of the specific enzymatic activity of microorganisms involved in periodontal disease. More sensitive and specific clinical parameters, taken together with other microbiologic methods, will be useful in daily clinical practice even before periodontal treatment.