The paper proposes a new method for discretisation of analogue control systems which guarantees the stability of the resulting digital control system for almost any sampling period and recovers the continuous-time performance when the sampling period approaches zero. In this method the digital control system is obtained such that its transfer function from the reference input to the plant input approximately matches that of the original continuous-time control system, such that the H-infinity-norm of the error transfer function is minimum. The effectiveness of the method is illustrated through an example.