In　this　study,　an　ultra-sensitive　method　for　the　quantification　of　lysozyme　based　on　the　Gd　3+　diethylenetriamine-N,N,N＇,N″,N″-pentaacetic　acid　labeling　and　capillary　electrophoresis-inductively　coupled　plasma　mass　spectrometry　(CE-ICP-MS)　was　described.　The　Gd　3+　-tagged　lysozyme　was　effectively　separated　by　capillary　electrophoresis　(CE)　and　sensitively　determined　by　inductively　coupled　plasma　mass　spectrometry　(ICP-MS).　Based　on　the　gadolinium-tagging　and　CE-ICP-MS,　the　lysozyme　was　determined　within　12min　with　an　extremely　low　detection　limit　of　3.89　attomole　(3.89×10　-11　molL　-1　for　100nL　of　sample　injection)　and　a　RSD<6%　(n=5).　The　proposed　method　has　been　successfully　used　to　detect　lysozyme　in　saliva　samples　with　a　recovery　of　91-106%,　suggesting　that　our　method　is　sensitive　and　reliable.　The　success　of　the　present　method　provides　a　new　potential　for　the　biological　assays　and　sensitive　detection　of　low-abundant　proteins.　©　2014　Elsevier　B.V.