Abstract: An adaptive filter concentrate flow control system and method includes a filter system, a pumping system driving feed fluid, concentrate and filtrate flowing through the filter system and a flow control system controlling the pumping system to maintain optimum filtrate flow rates or minimum feed flow rates along a control surface in a three dimensional transmembrane pressure--feed fluid rate--filtrate flow rate space. Actual sensed operating point data is used to locate the control surface so as to assure an optimized filtrate flow rate or minimized feed flow rate at which reversible blocking of the membrane has begun to occur without irreversible blocking or plugging. The system is advantageously employed to control and maximize the flow of plasma in a plasmapheresis system or to minimize the rate at which blood is withdrawn from a donor and introduced into the system while achieving a fixed rate of plasma flow.