Background: - Erythrocyte sedimentation rate (ESR) is still a widely used hematologicalrnparameter as indicator of disease condition. Westergren method is the standard method based onrnInternational committee for Standardization in Hematology (ICSH) recommendation forrnmeasuring ESR. But nowadays different automated instruments are available with reducedrnturnaround time, which increase the quality by reducing bio-hazard risk for the laboratoryrnprofessionals. However, there is no method comparison study conducted in Ethiopia and still thernold method is used in many health facilities.rnObjective: -Evaluation of Erythrocyte Sedimentation Rate measurement by IRIA automatedrnmethod and Westergren manual method at Myungsung Christian Medical Center, Addis Ababa.rnMethod: -A prospective cross sectional study was conducted at Myungsung Christian MedicalrnCenter from February to May 2017 GC. By doubling the ISCH recommendation the samplesrnwere tested in 3 different groups of values and the total sample size was 240. Every ESR orderedrnsample was analyzed using both manual and automated methods. Result was entered andrnanalyzed using SPSS version 20. Linear regression, correlation and Bland Altman analysis wererncarried out to determine agreement between the reference and the new method was carried out.rnAgreement was considered acceptable when the difference is lying between mean + two standardrndeviation (Mean+1.96SD) for 95% and above of cases in the Bland and Altman plot.rnResult: The comparison between the conventional Westergren and IRIA automated methodrnshowed very good correlation in the two methods and agree well for ESR level between 1-20rnmm/hr with r=0.934, Mean bias 0.663, SD 2.629,LoA(5.815, -4.490), and ESR level between 21-rn60 mm/hr r=0.917, Mean bias 0.1875, SD 3.7924 LoA (7.621,-7.246). However, for ESR levelrngreater than 60, it showed good correlation r=0.890 but poor agreement in the Bland-Altmanrnanalysis as the mean difference is lying between the limit of agreement for less than 95% ofrncases Mean difference 1.388, SD 11.346,LoA (23.625,-20.849).rnConclusion: For ESR level below 60 mm/hr, the two instruments can be used interchangeably.rnHowever, for ESR level greater than 60mm/hr the result of the automated machine must bernconfirmed with the conventional westergren method before using it for clinical propose.rnKey words: - Erythrocyte Sedimentation Rate, Westergren, IRIA, ESR automated