['Many countries use cooling plates to actively cool collected whole blood (WB) to room temperature. Until now, no paired comparison had been performed, and it was our aim to compare the effect of active versus no active cooling on the in vitro quality of WB and subsequently prepared blood components.', 'Two units of WB were pooled and divided shortly after donation. One unit was placed under a butane-1,4-diol plate to obtain active cooling; the other was placed in an insulated box with other warm units to mimic worst-case holding conditions. WB was held overnight and processed into a white blood cell (WBC)-reduced red blood cells (RBCs), buffy coat (BC), and plasma. The BCs were further processed into platelet (PLT) concentrates. RBCs were stored for 42 days, and PLT concentrates for 8 days (n\u2003=\u200312 paired experiments).', 'After overnight storage, ATP content of the RBCs was 4.9\u2003±\u20030.3\u2003µmol/g Hb for actively cooled WB versus 4.5\u2003±\u20030.4\u2003µmol/g\u2003Hb for not actively cooled WB (p\u2003<\u20030.001). On Day 42 of storage, RBCs prepared from this WB contained 3.1\u2003±\u20030.3\u2003µmol\u2003ATP/g\u2003Hb with active cooling versus 2.6\u2003±\u20030.3\u2003µmol/g\u2003Hb without (p\u2003<\u20030.001). Hemolysis on Day 42 was 0.35\u2003±\u20030.08% with active cooling and 0.67\u2003±\u20030.21% without (p\u2003<\u20030.001). No effect was observed on the in vitro quality of plasma, BC, or PLT concentrates.'] Does active cooling of whole blood to room temperature improve blood component quality?