The aim — of this study was to conduct a comparison of biochemical analytes determined in serum in order to identify bias of parameters of a capillary vs. venous blood sample. It was suggested that bias of certain biochemical analytes in serum of capillary blood compared with venous would be insignificant for the accuracy of clinical assessment of the patient’s health. Material and methods. The study was conducted on 51 conditionally healthy volunteers male and female. The paired difference in results obtained by different methods for each analyte was calculated in absolute and relative units according to the results of the statistical bootstrap. In addition, the comparison of average bias for each analyte was provided with the analytical variation (CVa) according to the formula reference change values (RCV, with the value CVi is equal to zero). Comparison of the results obtained with different types of biomaterial was also carried out using regression analysis and calculation of the determination coefficient (R2). Results. The investigated 19 analytes can be divided into 3 groups: I) statistically significantly decreasing in the serum of capillary blood against the venous, II) significantly increasing, and III) non-changing. II) This group includes 3 analytes: triglycerides (3.75%), iron (21.15%), creatinine (8.11%). III) This group includes 5 analytes: transferrin, total protein, AST, uric acid and urea. In addition, the bias of all the parameters studied, regardless of group, with the exception of iron (21.15%), fit into corresponding values of RCV and can be fully described by CVa. Conclusions. Most of the studied analytes may be determined in the serum of capillary blood without any harm to the accuracy of clinical assessment, provided that preanalytical rules are strictly followed. There is systematic clinically significant bias in the results of iron (21.15%) in the samples of serum of capillary blood.