Nanostructure-based　visual　assay　has　been　developed　for　determination　of　enzymatic　activity,　but　most　involve　in　poor　visible　color　resolution　and　are　not　suitable　for　routine　utilization.　Herein,　we　designed　a　high-resolution　colorimetric　protocol　based　on　gold/silver　core/shell　nanorod　for　visual　readout　of　alkaline　phosphatase　(ALP)　activity　by　using　bare-eyes.　The　method　relied　on　enzymatic　reaction-assisted　silver　deposition　on　gold　nanorod　to　generate　significant　color　change,　which　was　strongly　dependent　on　ALP　activity.　Upon　target　ALP　introduction　into　the　substrate,　the　ascorbic　acid　2-phosphate　was　hydrolyzed　to　form　ascorbic　acid,　and　then,　the　generated　ascorbic　acid　reduced　silver　ion　to　metal　silver　and　coated　on　the　gold　nanorod,　thereby　resulting　in　the　blue　shift　of　longitudinal　localized　surface　plasmon　resonance　peak　of　gold　nanorod　accompanying　a　perceptible　color　change　from　red　to　orange　to　yellow　to　green　to　cyan　to　blue　and　to　violet.　Under　optimal　conditions,　the　designed　method　exhibited　the　wide　linear　range　5-100　mU　mL-1　ALP　with　a　detection　limit　of　3.3　mU　mL-1.　Moreover,　it　could　be　used　for　the　semiquantitative　detection　of　ALP　from　20　to　500　mU　mL-1　by　using　the　bare-eyes.　The　coefficients　of　variation　for　intra-　and　interassay　were　below　3.5%　and　6.2%,　respectively.　Finally,　this　method　was　validated　for　the　analysis　of　real-life　serum　samples,　giving　results　matched　well　with　those　from　the　4-nitrophenyl　phosphate　disodium　salt　hexahydrate　(pNPP)-based　standard　method.　In　addition,　the　system　could　even　be　utilized　in　the　enzyme-linked　immunosorbent　assay　(ELISA)　to　detect　IgG　at　picomol　concentration.　With　the　merits　of　simplification,　low　cost,　user-friendliness,　and　sensitive　readout,　the　gold　nanorod-based　colorimetric　assay　has　the　potential　to　be　utilized　by　the　public　and　opens　a　new　horizon　for　bioassays.　©　2014　American　Chemical　Society.