Peroxynitrite,　the　product　of　the　fast　reaction　between　nitric　oxide　and　superoxide　radicals,　is　a　strong　oxidant　and　cytotoxic　agent　in　vivo.　It　can　attack　biological　molecules,　including　proteins,　lipids　and　DNA.　In　recent　years,　the　interactions　of　peroxynitrite　and　proteins　have　attracted　considerable　interest　because　peroxynitrite-mediated　protein　damage　has　been　found　in　a　variety　of　diseases.　In　this　paper,　we　discuss　the　potential　pathological　significance　of　protein　damage　induced　by　peroxynitrite　in　detail,　and　the　molecular　mechanisms　of　protein　modification　by　peroxynitrite　are　reviewed　as　well.　Moreover,　the　future　developments　of　the　interaction　between　peroxynitrite　and　protein　are　also　prospected.