Abstract: A control system for a vacuum milking system, and a method of controlling vacuum in such milking system. The system comprises an electric vacuum pump motor, a vacuum transducer for providing an output signal that varies as a function of changes in vacuum in the milking line and a variable frequency drive (VFD) connected to the vacuum pump motor and the transducer for controlling the speed of the motor. The VFD varies the frequency of the power signal it provides to the motor as a function of deviation between the output signal from the transducer, which the VFD is programmed to recognize as representative of vacuum, and a setpoint representative of vacuum.