A　method　for　determining　residues　of　four　botanical　insecticides　oxymatrine,　matrine,　rotenone,　and　azadirachtin　in　fish　by　liquid　chromatography-electrospray　tandem　mass　spectrometry　(LC-MS/MS)　is　described.　The　extraction　was　achieved　using　acetonitrile,　with　the　addition　of　sodium　chloride　to　induce　a　salting　out　effect　before　using　n-hexane　to　defat.　Chromatographic　separation　is　achieved　on　Phenomenex　Luna　C18　column　in　the　mobile　phase　composition　of　acetonitrile　and　5　mmol/L　ammonium　acetate　buffer　consisting　formic　acid　to　provide　protons　for　LC-MS/MS　analysis.　Accomplishing　with　the　matrix　matched　calibration　curves　to　compensate　for　the　matrix　effect,　the　quantitative　data　showed　good　linear　response　within　the　concentration　ranges　studied.　Detection　is　carried　out　using　positive-ion　electrospray　tandem　mass　spectrometry.　Calibrations　were　linear　over　a　working　range　of　0.5-50　μg/L　for　oxymatrine,　matrine,　rotenone,　and　2-200　μg/L　for　azadirachtin.　The　average　recoveries　and　the　relative　standard　deviation　ranged　from　88.6-95.7%　and　7.58-10.2%,　respectively,　in　spiked　fish　samples　at　concentration　levels　ranging　from　0.5　to　10　μg/kg　for　oxymatrine,　matrine,　and　rotenone　and　from　2　to　50　μg/kg　for　azadirachtin.　The　limits　of　detection　for　oxymatrine,　matrine,　rotenone,　and　azadirachtin　were　0.29,　0.37,　0.21,　and　1.4　μg/kg,　respectively.　The　method　is　accurate,　specific,　and　sensitive　for　the　analysis　of　the　studied　botanical　insecticides　residues　in　fish　samples.　©　2011　Springer　Science+Business　Media,　LLC.