Objective:To identify differentially expressed saliva proteins of oral lichen planus(OLP)patients by two-dimensional fluo-rescence difference electrophoresis(2-D DIGE)and mass spectrometry(MS).Methods:3 pairs of saliva samples from OLP patients and matched healthy adults were collected.Saliva proteins were separated by 2-D DIGE and identified by liquid chromatography-mass spectrometry(LC-MS).Results:SDS-PAGE examination showed that the electrophoresis bands were clear and protein loss was rare. Protein dots were highly reproducible by 2-D DIGE.In average,the abundance of (31 7 ±71 )saliva protein spots were found in OLP pa-tients.4 highly reproducible spots were identified to be secretory IgA1 ,zincα-2-glycoprotein,salivary amylase and serum albumin by LC-MS and they were at higher level in OLP patients than those in the healthy controls.Conclusion:Secretory IgA1 ,zincα-2-glyco-protein,salivary amylase and serum albumin are highly expressed in the saliva of OLP patients,and may be related to the occurrence and development of oral lichen planus.