An erythrocyte sedimentation rate (ESR) measurement instrument having a Blood Collection Configuration and an ESR Measurement Configuration. The ESR measurement instrument includes a sedimentation measurement tube having an hollow interior volume containing a predetermined quantity of blood sample diluting agent therewithin and being air/fluid sealed with respect to the ambient environment; and a blood collection tube having a hollow interior volume containing a predetermined quantity of anti-coagulant and being vacuum-sealed with respect to the ambient environment, and physically coupled to the air-sealed sedimentation measurement tube, by at least a portion of the sedimentation measurement tube being inserted within a portion of the hollow interior volume of the blood collection tube. The sedimentation measurement tube and the blood collection tube are maintained stationarily fixed relative to each other as a unitary assembly having a syringe-like form factor when the ESR measurement instrument is arranged in the Blood Collection Configuration. During this configuration, a needle-supporting connector can be connected to the blood collection tube and a sample of whole blood from a patient vacuum-drawn and injected into the blood collection tube. After the sample of anti-coagulated blood has been collected in the blood collection tube and the needle-supporting connector is disconnected therefrom, the air/fluid seal of the sedimentation measurement tube can be broken and then the sedimentation measurement tube can be manually plunged into and to the bottom of the hollow interior volume of said blood collection tube, using a single-handed operation to rearrange the ESR measurement instrument into the ESR Measurement Configuration. The anti-coagulated sample of blood fills up a substantially portion of the sedimentation measurement tube and mixes with the blood sample diluting agent to enable the blood plasma/erythrocyte cell (P/E) interface level within the sedimentation measurement tube to settle downwards toward the blood collection tube during a predetermined time period when said ESR measurement instrument is oriented in a gravity vertical position. By virtue of the present invention, the erythrocyte sedimentation rate (ESR) of the collected blood sample can be measured by determining how far the P/E interface level has moved against graduation markings formed along the length of the sedimentation measurement tube during the predetermined time period.