The　determination　of　citrinin　(CIT)　by　a　microsphere-based　flow　cytometric　immunoassay　(MFCI)　has　been　developed.　In　the　method,　the　carboxyl-modified　microspheres　were　conjugated　with　CIT-Ovalbumin　(OVA)　antigen.　CIT　competed　with　the　CIT-OVA　antigen　on　the　surface　of　the　microspheres　for　the　anti-CIT　McAb.　Under　the　optimised　conditions,　IC50　value　was　1.0　ng/mL　and　the　limit　of　detection　reached　0.005　ng/mL.　The　cross-reactivity　was　less　than　0.01%　against　each　of　the　four　mycotoxins　such　as　aflatoxin　B1　(AFB　1),　ochratoxin　A　(OTA),　zearalenone　(ZEA),　deoxynilvalenol　(DON).　In　the　work,　the　MFCI　could　accurately　determine　CIT　in　the　real　red　yeast　rice.　The　systematic　error　was　low　with　the　coefficient　of　variation　(CV)　from　5.24%　to　8.16%　by　the　MFCI.　The　mean　recovery　of　CIT　from　artificially　contaminated　red　yeast　rice　was　from　89%　to　94%,　with　CV　from　7.2%　to　8.7%.　The　experimental　data　showed　that　the　precision,　sensitivity　and　specificity　of　the　developed　MFCI　method　for　the　determination　of　CIT　were　satisfactory.　©　2012　Elsevier　Ltd.　All　rights　reserved.