Abstract There is a growing commercial and academic interest in polymeric composites filled with short fibers and/or glass or mica flakes. Here, the properties depend strongly on the flow induced morphology and on the distribution of residual stresses. To optimize processing and properties, it is important to know both the melt rheology and the orientation of the dispersed phase. The industrial formulations are notoriously very complex. However, it is possible to understand, and sometimes predict, their behavior by a systematic comparison with simpler, better known systems, i.e., suspensions. This review concentrates on two main aspects of flow of polymer melts containing anisometric particles, namely yield phenomena and orientation.