Objective To screen differentially expressed serum proteins by label-free quantitative proteomics in patients with atopic dermatitis,in order to discover serum protein markers for atopic dermatitis.Methods Serum samples were collected from 6 patients with atopic dermatitis and 6 healthy human controls.Then,the samples from the patients were pooled together,so with those from the controls.Proteins were extracted from the two joint serum samples followed by separation with one-dimensional sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE).Peptides were obtained by enzymolysis in protein gels,which were subsequently identified by high performance liquid chromatography tandem mass spectrometry.The Mascot software was used for database searching,and the Scaffold software for relatively quantitative analysis of proteins.Results Totally,76 proteins with a difference of greater than 1.5 folds were identified between the serum samples of patients with atopic dermatitis and controls.There were 50 up-regulated and 26 down-regulated serum proteins in the patients compared with the healthy controls.Among these differentially expressed proteins,26 were only detected in the sera of the patients,and 14 proteins in those of the controls.Conlusion Differences exist in the expression of serum proteins between atopic dermatitis patients and healthy people.