In　this　study,　the　tribological　behaviors　of　Mg56.5Cu27Ag5Dy11.5　bulk　metallic　glass　(BMG)　in　air　and　NaCI　solution　were　investigated　using　ball-on-disk　reciprocating　friction.　The　Mg56.5Cu27Ag5Dy11.5　BMG　exhibits　higher　strength　and　hardness　than　those　of　commercial　AZ31B　alloy　and　pure　Mg.　The　wear　rate　of　the　Mg56.5Cu27Ag5Dy11.5　in　air　is　3.8　x　10(-7)　mm(3).　mm(-1)　.　N-1,　which　is　superior　to　those　of　AZ31B　alloy　(7.3　x　10(-7)　mm(3).　mm(-1).　N-1)　and　pure　Mg　(6.5　x　mm(3)　.　mm(-1)　.　N-1).　The　wear　mechanism　of　Mg56.5Cu27Ag5Dy11.5,　AZ31　B,　and　pure　Mg　sliding　in　air　is　dominated　by　oxidation　and　abrasive　wear.　The　wear　rates　of　alloys　in　NaCI　decrease　in　the　following　order:　8.3　x　10(-7)　mm(3).　mm(-1).　N-1　for　pure　Mg,　6.3　x　mm(3)　.　mm(-1)　.　N-1　for　AZ31B,　and　5.4　x　mm(3)　.　mm(-1)　.　N-1　for　Mg56.5Cu27Ag5Dy11.5.　The　Mg56.5Cu27Ag5Dy11.5　and　pure　Mg　demonstrate　inferior　corrosion　resistance　in　NaCI　to　that　of　AZ31B.　Thus,　the　Mg56.5Cu27Ag5Dy11.5　and　pure　Mg　subject　to　tribocorrosion　controlled　by　synergistic　effects　of　abrasive　and　corrosive　wear,　which　results　in　a　large　wear　rate　during　sliding　in　NaCI.　The　possible　mechanism　of　corrosion　accelerating　wear　deterioration　is　discussed,　which　provides　the　guidance　for　the　improvement　in　the　tribocorrosion　resistance　of　Mg-based　BMGs　for　further　load-bearing　applications.　2016　Elsevier　B.V.　All　rights　reserved.