In　last　decades,　the　operator　theory　of　Krein　spaces,　Krein　space　approaches,　and　various　generalizations　of　frames　have　interested　many　mathematicians　due　to　their　potential　applications　in　mathematics　and　engineering.　This　paper　addresses　the　frame　theory　for　Krein　spaces.　We　present　some　properties　of　J-orthonormal　bases,　Parseval　frames　and　frames　for　Krein　spaces,　and　a　parametric　expression　of　all　duals　of　an　arbitrarily　given　frame　in　Krein　spaces.　This　study　shows　that　the　frame　theory　for　Krein　spaces　is　not　a　direct　generalization　of　the　frame　theory　for　Hilbert　spaces.