Background: A comparison study is crucial before launching a new medical device; therefore, we compared the Mission Ultra Hb Testing System with the Sysmex XN-3000 automated hematology analyzer in Thai adult males and non-pregnant adult females.Methods: Parallel studies were conducted using discarded venous K2ethylenediaminetetraacetic acid samples from participants requiring hematological investigations. According to the World Health Organization criteria, the participants were categorized as overall, anemia, and non-anemia for analysis.Results: Three hundred participants were included in this study. In all participants, near-perfect correlation and agreement were observed between the two methods for Hb measurement (r = 0.963, p < 0.001) with an interclass correlation coefficient (ICC) of 0.981 (95% confidence interval [CI]: 0.976-0.985) and Hct measurement (r = 0.941, p < 0.001) with an ICC of 0.965 (95% CI: 0.956-0.972). The sensitivity and specificity of the device in detecting anemia were 86.2% (95% CI: 79.7-91.2) and 98.6% (95% CI: 95.2-99.8), respectively. The area under the curve was 0.976 (95% CI: 0.963-0.989).The device showed average biases of 0.76 g/dl (95% limits of agreement [LOA]: −1.03 to 2.54) for Hb measurement and −2.73% (95% LOA: −9.28 to 3.82) for Hct measurement in all participants. Conclusion:Agreement between the Mission Ultra Hb Testing System and Sysmex XN-3000 was observed. The device was excellent for detecting anemia. However, the essential evidence showing biases of the Hb and Hct measurements obtained from the device was revealed. Laboratory interpretation should be carefully performed, particularly at the near cut-off values.