A　novel　adaptive　synchronization　method　is　proposed　for　two　identical　Rossler　and　Chen　systems　with　uncertain　parameters.　Based　on　Lyapunov　stability　theory,　we　derive　an　adaptive　controller　without　the　knowledge　of　the　system　parameters,　which　can　make　the　states　of　two　identical　Rossler　and　Chen　systems　globally　asymptotically　synchronized.　Especially,　when　some　unknown　uncertain　parameters　are　positive,　we　can　make　the　controller　more　simple　and,　besides,　the　controller　is　independent　of　those　positive　uncertain　parameters.　All　results　are　proved　using　a　well-known　Lyapunov　stability　theorem.　Numerical　simulations　are　given　to　validate　the　proposed　synchronization　approach.