This investigation analyzed, in a cross‐sectional study, the possible relationship between gingival crevicular fluid (GCF) elastase‐like protease (ELP) levels and the periodontal clinical parameters or the presence of specific bacteria in subgingival plaque. A total of 388 periodontal sites from 8 adult periodontitis patients were examined for plaque index (P1I), gingival index (GI), pocket depth (PD) and alveolar bone loss (ABL). GCF ELP levels were determined as ELP alpha‐1 protease inhibitor (ELP‐α1‐PI) complex levels with a commercially available ELISA. Subgingival plaque samples were tested for the presence ofBacteroides gingivalis, B. intermedius and Actinobacillus actinomycetemcomitansby indirect immunofluorescence (IF) microscopy. GCF ELP‐α1‐PI levels were then correlated with clinical periodontal indices and proportions of IF‐positive bacteria per site. Statistically significant positive correlations were found between GCF ELP‐α1‐PI concentrations and subgingivalBacteroides proportions. When the sites examined were analyzed depending on the level of each clinical parameter, the levels of these correlations changed.A. actinomycetemcomitancorrelated highly (r = 0.716) with ABL for sites with low GI score. The correlations between GCF ELP‐α1‐PI and B.gingivalis(r = 0.642) orB. intermedius(r = 0.774) were the highest for ABL ≤ 20% and PD ≤ 3 mm, respectively. The strong association between GCF ELP‐α1‐PI concentrations and subgingival bacteria previously associated with advancing periodontitis indicates that measurement of GCF ELP‐α1‐PI concentrations may be useful in the evaluation of periodontal sites, especially those