In a detection method for undesired double- or multiple-pulse states in an ultra-short-pulse laser system operated in the soliton regime and intended for generating femtosecond or picosecond pulses, comprising an amplifying laser medium for producing a laser emission, a laser resonator having at least one resonator mirror and a pump source, a first signal .mu. proportional to the pulse power P(t) or pulse energy averaged over the resonator cycle is measured for the laser emission. A second signal .nu. proportional to the square of the pulse power P(t), averaged over the resonator cycle, is measured for the laser emission, and the occurrence of a double- or multiple-pulse state is detected on the basis of a comparison of the measured signals .mu. and .nu..