In a process for the monitoring of leakage in the hydraulic pressure area of a membrane pump, processing is in a manner such that the point in time (t₃), at which the snifting process serving for leakage compensation is initiated, is monitored continuously and compared with a reference value (t₁), where a predetermined deviation (t₁-t₃) between two values (t₃ and/or t₁) triggers a leakage display.