This paper presents the effect of soil resistivity on grounding grid for 66 kV transmission towers in Brunei Darussalam. Four locations are considered to measure the soil resistivity and the ground resistance for the transmission tower. The soil analyses have been carried out by CYMEGRD simulation software and the rms errors of the four locations have been calculated. In case of grid analysis, the ground resistances, ground potential rise, step and touch voltages are calculated. The simulated ground resistance values are compared with the measured ground resistances and, are found to be in good agreement. In addition, the ground potential rise (GPR), step and touch potentials have also been estimated using the simulation software and, are observed to be lower than the acceptable limit.