The tracking problem for a class of uncertain chaotic systems with dead-zone nonlinearity in the input function is considered in this paper. With the dead-zone nonlinearity in the controller, the disadvantage can be eliminated. The knowledge about the dead-zone nonlinearity in the input is unnecessary. To make this controller physically realizable, an extended state observer is used to estimate the unknown information. Numerical simulations are carried out to show the effectiveness of the design with respect to Duffing oscillator.