AbstractGranulocyte elastase activity and α‐2‐macroglobulin (α‐2‐MG) were studied in the gingival crevicular fluid (GCF) from 3 categories of sites in 6 patients with gingivitis and 6 patients with periodontitis. 6 inflamed sites in each gingivitis patient were sampled on paper strips and 12 sites, 6 with and 6 without attachment loss and periodontal pockets, were selected in each periodontitis patient. To avoid the influence of increase GCF volume from deep pockets, the elastase activity and the α‐2‐MG were calculated per μl of GCF. The proteolytic activity of elastase was measured with a low molecular weight substrate and the antiprotease, α‐2‐MG, with ELISA. The measured activity could be ascribed to elastase that had been released into the gingival tissues and into the GCF prior to sampling. In the periodontitis patients, the sites with tissue destruction had a significantly higher elastase activity per site and per μl GCF and a significantly lower α‐2‐MG per μl than the 2 other categories of sites without tissue destruction. The destructive inflammation seems to be associated with increased release of elastase, either from more numerous or from more active granulocytes and with an increased proteolytic consumption of the inhibitor accompanied by the fast elimination of the protease‐inhibitor‐complex. In conclusion, the study shows a strong relationship between elastase activity and tissue destruction, a finding that supports the pathogenic theory of an involvement of granulocytes and their proteolytic enzymes in the mecha