Abstract: The invention is directed to a failure detection system and method for detecting malfunction of an optical amplifier module with one or multiple transmission channels. The failure detection system comprises a unit for measuring a performance parameter of the module; a unit for providing an expected performance parameter; and a comparator unit for receiving the performance parameter and the expected performance parameter and producing an error signal when the performance parameter substantially departs from the expected performance parameter. The system also includes a display/alarm unit for receiving the error signal and accordingly signaling failure of the module. The performance parameter is an output value of the module; a correspondence between an output value and an input value for a transmission channel; a figure of merit (FOM.sup.t=t); a set of gains (g) for all transmission channels; and the dynamic range of the amplifier module.