We　demonstrated　the　femtosecond　erbium-doped　all-fiber　lasers　mode-locked　with　graphene　oxide,　which　can　be　conveniently　obtained　from　natural　graphite　by　simple　oxidation　and　ultra-sonication　process.　With　proper　dispersion　management　in　an　all-fiber　ring　cavity,　the　laser　directly　generated　200　fs　pulses　at　a　repetition　rate　of　22.9　MHz　and　the　average　output　power　was　5.8　mW.　With　the　variation　of　net　cavity　dispersion,　output　pulses　with　pulse　width　of　0.2　similar　to　3　ps　were　obtained　at　a　repetition　rate　of　22.9　similar　to　0.93　MHz.　These　results　are　comparable　with　those　of　graphene　saturable　absorbers　and　the　superiority　of　easy　fabrication　and　hydrophilic　property　of　graphene　oxide　will　facilitate　its　potential　applications　for　ultrafast　photonics.　(C)　2012　Optical　Society　of　America