This　paper　investigates　three-party　password　authenticated　key　exchange　protocols　using　elliptic　curve　cryptosystem　(ECC).　We　first　show　that　the　direct　elliptic　curve　analog　of　Chien＇s　protocol　proposed　most　recently　is　vulnerable　to　off-line　dictionary　attack.　Thereafter,　we　present　an　enhanced　protocol　based　on　ECC.　Our　proposal　can　defeat　password-guessing　attacks　and　the　stolen-verifier　attacks.　And　yet,　it　is　also　efficient.　Furthermore,　we　can　provide　the　rigorous　proof　of　the　security　for　it.　Therefore,　the　protocol　is　quite　popular　in　low　resource　environments.