A method for monitoring the evolution of stray currents of a railway infrastructure, the railway infrastructure comprising: - rails laid on a ground and insulated from the ground by an insulation system, the rails defining at least one track section (S, S'); - substations generating a voltage, preferably DC, to supply a rail vehicle; and - a monitoring system comprising at least one ground-rail voltage sensor and at least one calculation unit (77, 79); characterised in that the railway infrastructure further comprises at least one stabilised current source, in that the monitoring method comprises an operating phase comprising at least the following steps: - emission of a stabilised current by each current source in at least one of the rails; - measurement of the voltage generated by the stabilised current between the rails and the ground by the at least one rail-ground voltage sensor; - calculation, by the calculation unit (77, 79), of the current (C2, C'2) flowing in each section (S, S') from the current source; and - analysis by the calculation unit (77, 79) of the voltage measured by the rail-ground voltage sensor and of the calculated current and detection of a possible degradation of the insulation between the rails and the ground, and in that, during the analysis phase, the calculation unit (77, 79) analyses the voltage measured by the ground-rail voltage sensor and the calculated current and detects a possible degradation of the insulation between the rails and the ground by comparing the measured voltage with a previous value of ground-rail voltage (T1, T2) on the one hand, and the calculated current with a previous value of the current (C1, C'1, C2, C'2) flowing in the rails on the other hand. - rails laid on a ground and insulated from the ground by an insulation system, the rails defining at least one track section (S, S'); - substations generating a voltage, preferably DC, to supply a rail vehicle; and - a monitoring system comprising at least one ground-rail voltage sensor and at least one calculation unit (77, 79); characterised in that the railway infrastructure further comprises at least one stabilised current source, in that the monitoring method comprises an operating phase comprising at least the following steps: - emission of a stabilised current by each current source in at least one of the rails; - measurement of the voltage generated by the stabilised current between the rails and the ground by the at least one rail-ground voltage sensor; - calculation, by the calculation unit (77, 79), of the current (C2, C'2) flowing in each section (S, S') from the current source; and - analysis by the calculation unit (77, 79) of the voltage measured by the rail-ground voltage sensor and of the calculated current and detection of a possible degradation of the insulation between the rails and the ground, - emission of a stabilised current by each current source in at least one of the rails; - measurement of the voltage generated by the stabilised current between the rails and the ground by the at least one rail-ground voltage sensor; - calculation, by the calculation unit (77, 79), of the current (C2, C'2) flowing in each section (S, S') from the current source; and - analysis by the calculation unit (77, 79) of the voltage measured by the rail-ground voltage sensor and of the calculated current and detection of a possible degradation of the insulation between the rails and the ground, and in that, during the analysis phase, the calculation unit (77, 79) analyses the voltage measured by the ground-rail voltage sensor and the calculated current and detects a possible degradation of the insulation between the rails and the ground by comparing the measured voltage with a previous value of ground-rail voltage (T1, T2) on the one hand, and the calculated current with a previous value of the current (C1, C'1, C2, C'2) flowing in the rails on the other hand.