Abstract: Erythrocyte Sedimentation Rate is determined by collecting a predetermined quantity of venous blood directly within a sealed evacuated ESR specimen tube which may contain a specific quantity of an anticoagulant, agitating the sealed specimen tube to mix thoroughly the anticoagulant with the blood, supporting the sealed specimen tube in a precise axially vertical position, and measuring the distance from the bottom of the surface meniscus to the top of the column of red cells at a predetermined time after the sealed specimen tube has been vertically positioned. The ESR specimen tube has a diametrically enlarged portion at one end fitted with a penetrable elastomeric sealing stopper and may be graduated along its length.