The invention relates to a magnetic-inductive measuring device for flowing substances with at least one subsystem respectively for carrying the substances, recording measuring signals through a signal pickup, generating a magnetic field through at least two exciting coils and a ferromagnetic core and bounding the measuring device on the ambient side of the housing. The measuring device is characterized in that at least one of the subsystems is entirely or partly formed by layers of fibre composite material and/or is embedded in layers of fibre composite material.