Graft-versus-host disease (GVHD) is the major life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT), developing in 35%-70% of all allo-HSCT recipients despite immunosuppressive prophylaxis. The recent application of proteomic tools that allow screening for differentially expressed or excreted proteins in body fluids could possibly identify specific biomarkers for GVHD. Whole saliva is highly attractive for noninvasive specimen collection. In the present study, we collected saliva specimens from 40 consecutives patients who underwent allo-HSCT between December 2008 and March 2011 at our institution. The specimens were analyzed by HPLC coupled to electrospray-ionization mass spectrometry. Variable expression of S100 protein family members (S100A8, S100A9, and S100A7) was detected. Fourteen of 23 patients with GVHD demonstrated the presence of S100A8, compared with only 2 patients without GVHD and 0 patients in the control group (P = . 001). S100A7 was detectable in 11 of the 23 patients with GVHD but was absent in the other 2 groups (P = VSports手机版. 0001). S100A9-short was detected in 20 patients with GVHD, in 9 patients without GVHD, and in 8 healthy volunteers (P = . 01) Further studies are needed to clarify the role of these proteins as a marker of GVHD or as an index of mucosal inflammation. .