This　paper　proposes　a　scalable　scheme　for　certificate　revocation　in　Public　Key　Infrastructure.　In　this　scheme,　the　set　of　revoked　certificates　is　divided　into　groups.　In　each　group,　proofs　for　certificate　status　are　computed　using　one-way　accumulators,　while　all　groups　are　still　organized　in　a　hash　tree.　The　main　advantage　of　the　proposed　scheme　is　that　it　can　adjust　traffic　between　CA-to-directory　and　directory-to-user　according　to　certificate　update　rate　and　query　rate　in　applications,　thus　overall　traffic　for　certicate　revocation　can　be　remarkably　reduced　and　a　wider　range　of　scenarios　can　be　accommodated.　Compared　with　Naor＇s　Dynamic　Hash　Tree　scheme,　results　show　it　can　reduce　traffic　by　about　50%　in　typical　environments.　©　2005　IEEE.