This paper addresses adaptive synchronization of coupled FitzHugh_Nagumo systems via active control. Using techniques from modern control theory, a novel adaptive controller and a parameter estimation update law based on Lyapunov stability theory are proposed, which can make the states of two identical Buri.. and Todorovi.. systems be global asymptotical synchronization in the presence of system?s unknown constant parameters. The effectiveness of the proposed scheme is demonstrated by theoretical analyses and a series of computer simulations.