Although　nitrite　effect　on　enhanced　biological　phosphorus　removal　(EBPR)　has　been　previously　studied,　very　limited　research　has　been　undertaken　about　the　effect　of　nitrite　accumulation　caused　by　nitritation　on　EBPR.　This　paper　focused　on　nitrite　effect　from　nitritation　on　EBPR　in　a　sequencing　batch　react　or　treating　domestic　wastewater.　Results　showed　that　nitrite　of　below　10　mg/L　did　not　inhibit　P-uptake　and　release;　whereas　EBPR　deterioration　was　observed　when　nitrite　accumulation　reached　20　mg/L.　Due　to　P-uptake　prior　to　nitritation,　nitrite　of　20　mg/L　has　no　effect　on　aerobic　P-uptake.　The　main　reason　leading　to　EBPR　deterioration　was　the　competition　of　carbon　source.　Batch　tests　were　conducted　to　investigate　nitrite　effect　on　anaerobic　P-release.　Under　sufficient　carbon　source,　nitrite　of　30　mg/L　had　no　impact　on　poly-beta-hydroxyalkanoate　(PHA)　storage;　contrarily,　under　insufficient　carbon　source,　denitrifiers　competing　for　carbon　source　with　phosphorus　accumulating　organisms　resulted　in　decrease　of　PHA　synthesis　and　P-release.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.