Control of an active suspension system with uncertain parameters is studied. A simple heave two-degree-of-freedom vehicle model is considered. A state variable feedback and an integral plus state variable feedback controllers are designed for the nominal system. A memoryless nonlinear feedback controller is superimposed on the nominal controllers to compensate for the uncertainties. The design of the robust controller does not require any a priori statistics for the uncertain parameters, only bounding sets are taken as given. Simulation studies show that the proposed controller results in better attitude control without sacrificing the ride comfort.