A　new　graphene　immunosensing　platform　based　on　a　new　electrochemical　immunosensor　was　designed　for　sensitive　screening　of　carcinoembryoninc　antigen　(CEA)　as　a　model　biomarker　in　clinical　immunoassay.　Gold　nanoflowers　and　single-stranded　DNA　(ssDNA)　molecules　were　initially　assembled　onto　the　surface　of　graphene　for　the　fabrication　of　the　electrochemical　immunosensor　using　layer-by-layer　strategy,　and　then　a　sandwich-type　immunoassay　format　was　developed　for　CEA　detection　based　on　gold　nanoflower-labeled　signal　antibodies.　Graphene　nanosheets　with　high　conductivity　and　biocompatibility　could　greatly　enhance　the　bound　force　with　ssDNA,　and　improve　the　analytical　properties　of　the　immunosensor.　Gold　nanoflowers　with　electrochemical　activity　provide　a　large　surface　area　for　the　label　of　biomolecules.　The　graphene　platform　displayed　a　good　electrochemical　behaviour　toward　the　detection　of　CEA.　Under　optimal　conditions,　the　electrochemical　immunosensor　exhibited　a　wide　dynamic　range　of　0.05　to　45ng　mL-1　with　a　relatively　low　detection　limit　of　0.01ng　mL-1　CEA　at　signal-to-noise　ratio　of　3.　Intra-　and　interassay　coefficients　of　variation　were　below　12%.　The　feasibility　of　the　electrochemical　immunosensor　was　evaluated　for　real-life　clinical　specimens,　and　no　significant　differences　at　the　95%　confidence　level　were　encountered　between　the　immunosensor　and　commercially　available　Roche　Elecsys　2010　Electrochemiluminescent　Automatic　Analyzer.　In　addition,　the　analytical　properties　of　the　immunosensor　were　comparatively　favourable　with　those　of　other　electrochemical　immunosensors.　©　2011　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.