Comparison of spectrophotometric methods for determining hemoglobin concentration, content and concentration of hemoglobin in erythrocytes Objectives: Blood count analysis plays a fundamental role in monitoring the patient's health status. Determination of the concentration of erythrocytes and hemoglobin and computational parameters of hemoglobin content and concentration in erythrocytes with hematological devices that work on different principles, different disease conditions can be detected. The aim of the research is to determine whether there is a statistically significant difference and whether devices can be used interchangeably in operation. Study design: A cross - sectional study. Material and methods: The research includes 50 randomly selected blood samples collected by standard blood collection procedures and analyzed on two hematology analyzers. The comparability of the methods was tested using Passing - Bablok regression analysis and Bland - Altman diagram. Results: The excellent connection between the methods was determined by Spearman's correlation coefficient. The significance levels obtained by the Mann - Whitney test correspond to the set significance level of P < 0,05, and there is no statistically significant difference. Passing - Bablok regression analysis with certain confidence intervals showed a constant deviation for hemoglobin, and a proportional and constant deviation for MCHC, while there is no deviation for MCH. Bland - Altman analysis showed a scatter of results, some of which are outside the limits of standard deviations. Conclusion: Between the methods on different analyzers, it has been proven that the methods are comparable with deviations that are not significant and can be used interchangeably in the routine work of the laboratory.