This paper presents a new design method for an active suspension control system based on H∞ optimization robust control theory. A four-degrees-of-freedom half-car model equipped with independently controlled from and rear active suspensions is analyzed. Time, frequency and spectral analyses show that the active suspension maintains the tire-road contact force for good maneuvering, stability and handling, reduces the vibration transmissibility and attenuates the passenger-perceived acceleration, improving the ride comfort. The robustness properties of the H∞-optimization-based suspension controller are examined and compared with those of a conventional LQC-based active suspension.