Control of blood pressure and cardiac output, with dopamine and sodium nitroprusside has been achieved using a model reference adaptive controller. A procedure for selecting the adaptation weights for a 2×2 system has been developed. Satisfactory model following has occurred despite time delays that caused stability criteria to be violated. The structure of the plant prohibited zero steady state error in some cases, even when the parameters were known. However, the resulting plant response is allowable from a physician's viewpoint. The adaptive controller is compared with a nonadaptive controller, showing the motivation for adaptive control.