In the HPLC high-resolution ESI-MS profiles of Gingival Crevicular Fluid, four proteins, with exp. monoisotopic ion [M+H]+ at 3440.54 ± 0.06 m/z, 3369.50± 0.06 m/z, 3484.51 ± 0.06 m/z and 3707.77 ± 0.06, eluting between 24.5-26.6 minutes, were detected. The monoisotopic mass values and the manual inspection of the high-resolution MS/MS spectra of the ions at [M+5H]+5 at 689.31, 675.10, 698.11 and 742.76 m/z, and of the ions at [M+4H]+4 at 843.63, 872.39 m/z allowed to establish that the four proteins were alpha defensins 1, 2, 3 and 4.