A single pass automated blood collection system for collecting red blood cells and plasma from a donor comprising: a reusable hardware component; and a pre-assembled disposable fluid circuit component configured to interface with the hardware component, the disposable component comprising: a donor access device for withdrawing whole blood from a donor; a leukoreduction filter; a source of anticoagulant communicating with the donor access device; a blood separation device communicating with the access device and employing relatively rotating surface, at least one of which carries a membrane substantially permeable to plasma and substantially impermeable to red blood cells to separate the whole blood into substantially concentrated red cells and plasma; a first collection container communicating with the blood separation device for receipt of the substantially concentrated red blood cells; a source of preservative solution communicating with the first collection container; and a second collection container communicating with the blood separation device for receipt of the plasma; the reusable hardware component further comprising a first clamp for controlling communication between the donor access device and the blood separation device, a weigh scale associated with the first collection container, a controller configured to close the first clamp in response to a signal from the weigh scale indicating that the first collection container contains a predetermined volume of concentrated red blood cells, and a first pump for transporting whole blood to the blood separation device; wherein the leukoreduction filter is located upstream of the first pump. a reusable hardware component; and a pre-assembled disposable fluid circuit component configured to interface with the hardware component, the disposable component comprising: a donor access device for withdrawing whole blood from a donor; a leukoreduction filter; a source of anticoagulant communicating with the donor access device; a blood separation device communicating with the access device and employing relatively rotating surface, at least one of which carries a membrane substantially permeable to plasma and substantially impermeable to red blood cells to separate the whole blood into substantially concentrated red cells and plasma; a first collection container communicating with the blood separation device for receipt of the substantially concentrated red blood cells; a source of preservative solution communicating with the first collection container; and a second collection container communicating with the blood separation device for receipt of the plasma; the reusable hardware component further comprising a first clamp for controlling communication between the donor access device and the blood separation device, a weigh scale associated with the first collection container, a controller configured to close the first clamp in response to a signal from the weigh scale indicating that the first collection container contains a predetermined volume of concentrated red blood cells, and a first pump for transporting whole blood to the blood separation device; wherein the leukoreduction filter is located upstream of the first pump. a donor access device for withdrawing whole blood from a donor; a leukoreduction filter; a source of anticoagulant communicating with the donor access device; a blood separation device communicating with the access device and employing relatively rotating surface, at least one of which carries a membrane substantially permeable to plasma and substantially impermeable to red blood cells to separate the whole blood into substantially concentrated red cells and plasma; a first collection container communicating with the blood separation device for receipt of the substantially concentrated red blood cells; a source of preservative solution communicating with the first collection container; and a second collection container communicating with the blood separation device for receipt of the plasma; the reusable hardware component further comprising a first clamp for controlling communication between the donor access device and the blood separation device, a weigh scale associated with the first collection container, a controller configured to close the first clamp in response to a signal from the weigh scale indicating that the first collection container contains a predetermined volume of concentrated red blood cells, and a first pump for transporting whole blood to the blood separation device; wherein the leukoreduction filter is located upstream of the first pump.