Abstract: The present invention relates to a multilayer structure based on polyamides and graft copolymers having polyamide blocks, comprising, in this order: a) a first layer (1) formed from a polyamide (A) or else a polyamide (A)/polyolefin (B) blend having a polyamide matrix; b) optionally, a tie layer (2a); c) a layer (2) based on a graft copolymer having polyamide blocks, formed from a polyolefin backbone and from at least one polyamide graft in which: the grafts are attached to the backbone by the residues of an unsaturated monomer (X) having a functional group capable of reacting with a polyamide having an amine end group; the residues of the unsaturated monomer (X) are attached to the backbone by grafting or copolymerization via its double bond; the layers (1), (2a) and (2) being successive and adhering to one another in their respective contact region.