In this paper, a robust output-feedback adaptive control is proposed for linear time-invariant (LTI) single-input single-output (SISO) plants with unmeasurable input disturbance. Using dynamic surface control (DSC) technique, it is shown that the explosion of complexity problem in backstepping control can be eliminated. Furthermore, the proposed adaptive DSC scheme has the following merits: 1) by introducing an initialization technique, the L ∞ performance of system tracking error can be guaranteed even if the plant high-frequency gain is unknown and the input disturbance exists, and 2) the adaptive law is necessary only at the first design step, which significantly reduces the design procedure. It is proved that with the proposed scheme, all the closed-loop signals are semiglobally uniformly ultimately bounded. Simulation results are presented to demonstrate the effectiveness of the proposed scheme. In this paper, a robust output-feedback adaptive control is proposed for linear time-invariant (LTI) single-input single-output (SISO) plants with unmeasurable input disturbance. Using dynamic surface control (DSC) technique, The proposed adaptive DSC scheme has the following merits: 1) by introducing an initialization technique, the L ∞ performance of the system tracking error can be guaranteed even if the plant high-frequency gain is unknown and the input disturbance exists, and 2) the adaptive law is necessary only at the first design step, which significantly reduces the design procedure. It is proved that with the proposed scheme, all the closed-loop signals are semiglobally classified ultimately bounded Simulation results are presented to demonstrate the effectiveness of the proposed scheme.