A new misfit dislocation multiplication process has been observed for the first time in InxGa1−xAs/GaAs strained-layer superlattices (withx<0.20). Transmission electron microscopy reveals that this process is based on the occurrence of interactions between perpendicular 60° misfit dislocations with identical Burgers vectors and cross-slip events on the resulting dislocation configurations. The last stage of the process involves the operation of Frank-Read sources that emit glissile dislocations into the {111} planes; parts of the half-loops which develop towards the superlattice are parallel to the interface and are then new misfit dislocations.