In this paper we present a robust controller design methodology for vehicle rollover prevention utilizing active steering. Control design is based on keeping the magnitude of the vehicle load transfer ratio (LTR) below a certain level in the presence of driver steering inputs; we also develop an exact expression for LTR. The proposed controllers have a proportional-integral structure whose gain matrices are obtained using the results of Pancake et al. (2000) (T. Pancake, M. Corless and M. Brockman, "Analysis and control of polytopic uncertain/nonlinear systems in the presence of bounded disturbance inputs'', Proceedings of the American Control Conference, Chicago, IL, June 2000; T. Pancake, M. Corless and M. Brockman, "Analysis and control for a class of uncertain/nonlinear systems in the presence of bounded disturbance inputs'', 2007). These controllers reduce the transient magnitude of the LTR while maintaining the steady state steering response of the vehicle. The controllers can be designed to be robust with respect to vehicle parameters such as speed and centre of gravity height. We also provide a modi. cation to the controllers so that they only activate when the potential for rollover is significant. Numerical simulations demonstrate the efficacy of our approach and the resulting controllers.