A　new　electrochemical　immunoassay　protocol　for　the　determination　of　carcinoembryonic　antigen　(CEA)　in　human　serum　was　developed　by　means　of　immobilizing　horseradish　peroxidase-labeled　anti-CEA　antibodies　(HRP-anti-CEA)　on　the　nanogold/nano-Fe3O4　particles-functionalized　polyion　complex　(PIC)　membrane.　With　a　one-step　immunoassay　format,　the　formed　immunocomplex　inhibited　partly　the　bioactive　center　of　the　immobilized　HRP,　and　decreased　the　HRP　toward　the　reduction　of　H2O2.　Nanogold-actuated　nano-Fe3O4　mimetic　peroxidase　was　used　for　the　sensitivity　improvement　of　the　electrochemical　immunosensor　with　Prussian　blue　(PB)　as　mediators.　Under　optimal　conditions,　the　electrochemical　immunosensor　displayed　a　wide　dynamic　range　of　0.1-220ngmL-1　with　a　relative　low　detection　limit　(LOD)　of　10pgmL-1　CEA　(at　3σ).　Intra-　and　inter-assay　show　good　precisions　with　a　coefficient　of　variation　(CV)　lower　than　7.8%　and　7.3%,　respectively.　No　significant　difference　at　the　95%　confidence　level　was　encountered　in　the　analysis　of　17　human　serum　specimens　between　the　electrochemical　immunosensor　and　automatic　electrochemiluminescent　(ECL)　analyzer　for　the　determination　of　CEA.　©　2010　Elsevier　B.V.