A pump control system (20) for a pump (21) in a gas turbine engine (10) is described. The pump control system (20) comprises demand means (22) for providing a demand signal (23) relating to a required rate of fluid flow and/or pressure from the pump (21). The system also comprises sensing means (26) to sense at least one parameter of fluid downstream of the pump (21) and to provide at least one feedback signal (28) relating to the, or each, respective parameter. Comparator means (30) is provided for comparing the demand signal (23) with the, or at least one, feedback signal to provide a control signal (33) for controlling the pump.