A blood processing system is disclosed which is adapted for single or double access draw and return. The blood processing system includes a blood processor for separating blood (or blood components) into one or more components or other components. In one embodiment the blood processor includes an inlet for receiving blood from blood source and an outlet for returning at least one blood component to the source. The processing system includes a first flow path in communication with the inlet, a second flow path in communication with the outlet, a third flow path in communication with a second flow path at two spaced apart locations, a reservoir communicates with the third flow path between the two spaced apart locations, and a flow communication site associated with the second flow path downstream of the spaced apart locations which communication site is adapted to permit communication with the first flow path.