A method and an apparatus for use in an earth-fault protection in a three-phase electric network, the apparatus is configured to detect a phase-to-earth fault in the network, to determine for each of the phases of the network a phase current during the fault or a change in the phase current due to the fault, to detect a faulted phase of the network, to determine an estimate of an earth-fault current on the basis of the faulted phase and the phase currents or the changes in the phase currents, to determine a zero-sequence voltage of the electric network or a change in the zero-sequence voltage, and to determine a direction of the phase-to-earth fault from the measuring point on the basis of the estimate of the earth-fault current and the zero-sequence voltage or the change in the zero-sequence voltage.