The doctoral dissertation describes the maintenance of the of the group resistance standard in the Primary Electromagnetic Laboratory. Two methods are described for the standard resistor comparison for nominal ratios of 1:1 and 1:10 with the help of two digital voltmeters Hewlett Packard 3458A. The measurement procedure is automatized with the help of PC computer and PC controlled cards and devices. All necessary auxiliary devices, programs and schemes have been made and described. The computer does statistical analysis of the results and generates reports with important data. The special attention was given to all uncertainty contributions such as thermal EMF, contact resistances, leakage resistances, temperature, humidity and pressure. The special methods have been developed for the determination of voltmeter linearity error and for determination of the resistor load coefficients. The measurement uncertainty has been estimated, both for the comparison procedure, and for each of the standard resistors. Two measurement methods have been developed: method MOEO 1.1 is more suitable for the comparison of standard resistors up to 10 kΩ, because the connecting wire does not influence the measurement in this method, and the measurement method MOEO 1.2 is more suitable for the comparison of standard resistors with higher nominal value, because in this method the DVM input impedance and the leakage resistances towards the ground do not influence the measurement. The analysis of change through time for all standard resistor and the program for the extrapolation of values into the ‘future’ between the comparisons has been made. With the development of these methods, a system of traceability has been established for the standard resistors in the Republic of Croatia, which is one of the main goals of the Primary Electromagnetic Laboratory.