Abstract: A median filter includes a number of identical modules each arranged simultaneously to receive the current value of an imcoming digital signal. Each module includes a feedback shift register of special design enabling it to be set to receive its input to any one of its stages. The shift registers of the different modules are set to receive their inputs at different stages and logic means is associated with each shift register for comparing the content of one stage with the contents of each other stage to determine whether the content of that said one stage is the medium value. If it is the median value it is passed to an output of the circuit.