In recent years, the use of glass fiber reinforced plastic has steadily increased. Because of the good weight-specific properties, fiber reinforced plastics are especially attractive for use in lightweight applications. The mechanical properties of fiber reinforced plastic parts mainly depend on the present fiber length in the component. During processing, the fiber length is reduced by the shear stress transferred from the polymer melt to the fibers. In order to describe the occurring fiber length degradation, it is necessary to know the fiber orientation, because fiber-fiber interactions and the hydrodynamic forces acting on the fibers depend strongly on the fiber orientation in the polymer melt. The experimental study focuses on investigating the influence of the fiber volume fraction and the shear rate on the fiber orientation and which impact the change in orientation has on the fiber length degradation. Additionally, the influence of the fiber volume fraction on the rheology of polypropylene melts is investigated. In order to reduce the number of influencing factors, the investigations are carried out in a simple shear flow.