Polymorphonuclear leukocytes (PMN) play a critical role in the host's response to the subgingival microflora. Interleukin-8 (IL-8) is a potent chemotactic and activating factor for PMN. In this study, the presence of IL-8 in gingival crevicular fluid (GCF) was examined in relation to the PMN indicator beta-glucuronidase (beta G), as well as clinical parameters of chronic inflammatory periodontal disease. Data was obtained from 30 patients with periodontitis and 14 healthy controls. For the control group, GCF and clinical data were obtained only once. For the periodontitis patients, clinical data and GCF samples were collected prior to treatment, and GCF samples were again collected 2 weeks after scaling and root planing. Comparing control and periodontitis patients prior to treatment, IL-8 concentration was lower in the patients with periodontitis. Scaling and root planing resulted in either an increase or a decrease in total IL-8 and IL-8 concentration GCF. A reduction in total IL-8 or IL-8 concentration was accompanied by a corresponding reduction in beta G activity. An increase in total IL-8 or IL-8 concentration after scaling and root planing was associated with an increase in beta G activity in some patients and a reduction in beta G activity in other patients. The periodontitis patients who did not demonstrate a linkage between IL-8 and beta G activity in GCF were those individuals with the highest beta G activity prior to treatment. As elevated beta G activity in GCF has been associated with an increased risk for probing attachment loss, the absence of a direct relationship between IL-8 in GCF and PMN recruitment into the gingival crevice may characterize individuals at risk for progression of periodontitis.