A new automated erythrocyte sedimentation rate (ESR) system, the SEDISYSTEM was evaluated for its stability and accuracy. It offers automated mixing of vacuum-collected blood for 5 minutes (min) and reading of the ESR for 20 min to generate values comparable with those of the Westergren method at 1 hour (h) and 2 h. The benefits are (1) simplified procedure, (2) reduction of biohazard and, (3) shortening of examination time. To evaluate the basic performance of this system, the stability of ESR values was first evaluated by keeping samples at room temperature for up to 20 h, during which time no remarkable change was observed. Next, a comparison between this system and the standard method of Westergren was conducted and good agreement was obtained. To determine the factors affecting ESR values, correlations were analyzed between the ESR obtained by SEDISYSTEM and the standard Westergren method for red blood cell concentration, hematocrit, and plasma proteins including fibrinogen, albumin and globulins (alpha1, alpha2, beta and gamma). Multiple regression analysis showed significant correlation with RBC, fibrinogen and gamma globulin. It is concluded from these results that SEDISYSTEM is a useful new tool for the measurement of ESR.