A　new　electrochemical　immunoassay　strategy　for　direct　detection　of　carcinoembryoninc　antigen　(CEA)　in　serum　was　developed　by　using　multiarmed　star-like　platinum　nanowires　(PtNWs)　with　biomolecular　assembly　as　signal　tags　on　an　anti-CEA-functionalized　graphene　sensing　platform.　Initially,　the　PtNWs　were　synthesized　via　a　wet　chemical　method,　and　then　the　synthesized　PtNWs　were　used　for　the　co-immobilization　of　CEA　and　horseradish　peroxidase　(HRP).　Compared　with　platinum　nanoparticles,　the　prepared　PtNWs　could　provide　a　large　room　for　the　conjugation　of　HRP　and　CEA.　With　a　competitive-type　immunoassay　format,　the　assay　was　performed　in　two　types　of　supporting　electrolytes　including　new　born　cattle　serum　(NBCS)　and　acetate　buffer　solution　(ABS,　pH　5.5),　respectively.　Similar　detection　limit　(LOD)　of　5.0pgmL-1　vs.　1.0pgmL-1　but　narrower　dynamic　working　linear　range　of　0.01-60ngmL-1　vs.　0.002-80ngmL-1　was　obtained　toward　CEA　standards　in　the　NBCS　compared　to　the　ABS.　The　intra-assay　coefficients　of　variation　(CVs)　were　4.3%,　8.6%,　and　6.2%　at　0.05,　10,　and　40ngmL-1　CEA,　respectively,　while　the　inter-assay　CVs　were　7.6%,　10.5%,　and　8.9%　at　the　above-mentioned　levels,　respectively.　In　addition,　the　selectivity　and　stability　of　the　electrochemical　immunosensor　were　acceptable.　Importantly,　the　developed　method　was　used　to　assay　clinical　serum　specimens,　receiving　a　good　relation　with　those　obtained　from　the　referenced　method.　©　2011　Elsevier　B.V.