The overall dialysis coefficient is a basic characteristic of a continuous dialyzer. Its determination is based oil the Measurement of concentrations and volumetric liquid flow rates of the streams entering and leaving the dialyzer; generally, all these parameters can be loaded with an experimental error. The paper focuses oil the transformation of these errors into the final results. Using the generated precise experimental data, small random errors have been introduced into them and the effect of these errors upon the overall dialysis coefficient has been evaluated. The error analysis has proved that large errors of the overall dialysis coefficient can be expected if low volumetric liquid flow rate and intensive mass transfer exist. Moreover, the effect of errors of input parameters can be eliminated to a large extent using reconciled experimental data measured.