A rigorous evaluation of the influence of a transcrystalline interphase on the adhesion between a fibre and a polymer matrix is difficult because it is generally not possible to consider this parameter without other factors. Indeed, in the case of a reinforcing material allowing spontaneous transcrystallization of a thermoplastic matrix, the inhibition of this phenomenon is, for instance, possible by modifying the surface topography or the physico-chemical nature of the fibre by appropriate coatings. In the same way, the fibres which do not intrinsically favour transcrystalline growth can behave as active substrates by applying a shear stress onto the fibre-matrix interface. In this case, however, processing of the sample for the classical micromechanical tests remains extremely difficult. In order to understand better the participation of a transcrystalline interphase in the interfacial adhesion in a polypropylene-glass fibre system, an experimental protocol has been developed which allows us to evaluate the evolution of the interfacial shear stress during the matrix crystallization, the latter being spherulitic or cylindritic. The results show that a transcrystalline interphase in a polypropylene-glass fibre composite does not significantly alter the adhesion between the two materials after total crystallization of the matrix. Nevertheless, it is shown that an important hooping of the fibre occurs during the development of a transcrystalline superstructure.