A plasma concentrator of this invention having a concentrator chamber, concentrator gel beads, a filter, and an agitator. The agitator has agitator blades extending outwardly from the lower end. The agitator end is positioned in the concentrator chamber and supported for rotation about its central axis and for reciprocal movement along its central axis. The concentrator has a top with an upper opening through which the upper end of the actuator stem extends, and a lower opening in which the filter is positioned. The concentrator chamber can have a cylindrical inner wall, and the agitator blades can have an outer edge in close proximity to the inner wall with the space between the outer edge and the inner wall being less than the diameter of the gel beads. The filter is selected to block effective flow of plasma therethrough under ambient gravity conditions and permit plasma and plasma concentrate flow therethrough under centrifugal forces of the separation gravity. The method concentrates plasma by removing water without significantly denaturing the fibrinogen in the plasma. The plasma is introduced into a concentration chamber containing a plurality of dehydrated concentrator gel beads and an agitator. Then water is removed from the plasma while stirring the beads to reduce plasma polarization and breaking up clumps of beads that form during the agitation. Then centrifugal force can be applied to the concentrated plasma in an amount sufficient to separate a substantial portion of the plasma concentrate from the beads.