Abstract: A combined cardiotomy and venous blood reservoir according to a preferred embodiment of the invention provides a separate in-flow path for both cardiotomy fluid and for venous blood, and includes a cardiotomy fluid filter element also serving as an initial de-foamer. The cardiotomy fluid is de-foamed, filtered, and again de-foamed. The venous blood is de-foamed, and then both fluids are combined for flow from the reservoir. The filter area provided for cardiotomy fluid is advantageously separated from the area of a final de-foamer element. Thus, both the cardiotomy fluid and venous blood may flow through this final de-foamer element simultaneously along separate flow paths. The reservoir design provides greater freedom in selecting adequate filter area for the cardiotomy fluid, while allowing the selection of effective de-foamer element areas in order to achieve acceptable flow rates for both cardiotomy fluid and for venous blood under various conditions of operation for the reservoir.