The ultrafast pump‐probe signal of a two band semiconductor amplifier is theoretically analysed using Maxwell‐Semiconductor‐Bloch equations. It is shown that the coupling of the pump and probe pulse via the probe gain modification significantly contributes to the signal for short delay times between pump and probe. The probe signal exhibits dominant oscillatory interference‐like structures which conceal intensity dependent ultrafast features. Despite the semiconductor is described with a two band model which does not include free carrier absorption and two photon absorption the results are qualitatively similar to those of recent experiments. ©1995 American Institute of Physics.