When　mobile　users　retrieve　interested　location　information　through　location　based　service　(LBS),　they　should　always　provide　their　accurate　location,　which　may　leak　their　location　privacy.　In　order　to　prevent　privacy　leakage　when　service　provider　is　not　reliable,　some　solutions　based　on　two　ties　architecture　are　proposed.　However,　these　solutions　are　either　hard　to　implement　or　may　lead　to　huge　communication　cost.　In　this　paper,　we　present　a　novel　technique,　called　Guess-Answer.　Through　the　interaction　between　user　and　server,　the　location　information　within　a　region　that　satisfies　the　minimum　privacy　requirement　of　the　user　would　be　delivered.　Through　proper　analysis　and　experimental　study,　we　demonstrate　that　Guess-Answer　is　an　efficient　and　effective　way　to　achieve　personalized　privacy.　©　2011　Springer-Verlag　Berlin　Heidelberg.