Abstract 3 acute phase proteins, from the local gingival inflammatory response, were examined for their ability to distinguish healthy, gingivitis and periodontitis sites. Indirect competitive immunoassays were developed for the quantification of α2-macroglobulin (α2-M) and transferrin (TF), and for α1-antitrypsin (α1-AT), a double antibody sandwich assay was produced. Healthy (25), gingivitis (31) and periodontitis (28) sites were sampled with filter paper strips (2×13 mm) and the volume assessed with the Periotron 6000. The samples were eluted in phosphate-buffered saline and analyzed for α2-M. α1-AT and TF. The results were expressed as absolute amounts per sample (ng/30 s) and on a concentration basis (ng/μl of GCF). Higher GCF absolute amounts of α2-M, α1-AT and TF were consistently obtained from diseased (gingivitis and periodontitis) sites than healthy sites (p < 0.005). Absolute amounts of GCF α2-M. α1-AT and TF were increased in periodontitis sites over gingivitis sites, although these differences were not statistically significant (p > 0.1). When the results were expressed on a concentration basis, α2-M levels from diseased sites were significantly higher than healthy sites (p < 0.01). In addition. GCF TF concentration was increased in periodontitis compared to healthy sites (p= 0.03).