The sources of error in measuring high surge voltages with resistor, capacitor and mixed dividers have been investigated, and the responses of resistor and capacitor dividers to chopped waves have been compared with that of a shielded resistor divider in which the effect of earth capacitance has been eliminated.Errors arising from inductance in the connections between the divider and test object, and from the characteristics of the delay cable, have also been considered.Constructional details are given of dividers used at the National Physical Laboratory.