Abstract The adhesion of a blend of liquid-crystalline polymer (LCP) with polypropylene (PP) to the surface of glass fibres has been investigated in the whole range of blend composition. It was found that the composition dependence of the adhesion strength is characterized by a sharp increase when the amount of LCP in the blend exceeds a definite limit corresponding to phase inversion. The results are explained by the formation near the interface of two adhesion layers: the first is composed of pure LCP and has a higher surface tension, whereas the second layer represents the blend of varying composition. At small amounts of LCP adhesion failure proceeds in the interphase between the LCP and the blend. After phase inversion, where the adhesion strongly increases, adhesion failure proceeds near the interface between the LCP and the glass.