This work proposes an approximate output regulation of a class of nonlinear systems with time-varying disturbances. Since the implicit manipulated input cannot be solved exactly, a novel input/output linearized framework based on the Lyapunov function is developed. Through the step-by-step systematic design and an applied numerical method, the developed nonlinear controller is found to be a dynamic and state feedback. In terms of a certain invariant manifold, an approximate output regulation design without the need of derivative information of disturbances is proposed. The synthesis of dynamic feedforward/feedback controller includes only one tuning parameter, and is equivalent to a low-and-high gain approach. It is ensured that satisfactory tracking performance can be achieved with only instantaneous values of the exogenous signal available. Moreover the robustness of the system would be enhanced. Finally, an illustrative CSTR example is given to demonstrate the regulation control developed here. (C) 2000 Elsevier Science Ltd. All rights reserved.