Melt blending of Liquid Crystalline Polymers (LCP’s) with thermoplastic polymers often results in fiber forming of the minor LCP component during processing and hence gives an "in situ" improvement of the mechanical properties. The molecular processes like the miscibility between the two components play an important role both in the fiber formation and the self-reinforcement. These processes are often studied with DSC or Dynamic Mechanical Thermal Analysis (DMTA). Dielectric spectroscopy however has the clear advantage of the wide frequency and temperature range covered. Furthermore, this technique makes it also possible to evaluate processes which take place on the interfaces of a blend. Two of these systems (Vectra, the LCP, with polycarbonate resp. Noryl) have been studied owing to their difference in fibril break-up. The analysis has been carried out using mainly dielectric spectroscopy. DSC and DMTA measurements as well as electron microscopy have been carried out for the purpose of comparison. In blends of Vectra and polycarbonate partial miscibility as well as interactions between the components occur. In Vectra/Noryl blends phase separation in the Noryl takes place. No interactions between the components occur. The thermal treatment of the sample appears to determine largely the phase behaviour.