Specially molded plastic Vacu-tec collection cuvettes containing 0.25 ml of a 0.105 mol/L sodium citrate solution and one ml of blood are placed in the Ves-matic Easy cuvette holders at an 18° angle. The Boycott phenomenon allows erythrocytes to sediment more rapidly down the wall of an angled tube than when falling vertically. Sedimentation of erythrocytes is measured optically. Results equivalent to the one hour or two hour Westergren method can be obtained in 20 or 40 minutes respectively. Ten samples can be evaluated simultaneously even when started at different times.