The diamagnetic susceptibility χmof a series of low-density PE samples has been investigated with regard to the number of chain defects in the solid and in the liquid state. The diamagnetic susceptibility of PE rises gradually at the beginning of the melting interval, reaching a plateau which characterizes the diamagnetism of the liquid state. The percent increase in diamagnetism, δ χ, when passing from the solid to the liquid state is primarily due to an increase of intermolecular disorder of the crystalline segments and is apparently independent of the nature (conformation) of the lamellar surface. The increase of diamagnetism of liquid PE with the number of defects favors the view of a state of local molecular order in molten PE. Since the thickness of the crystalline lamellae decreases with the concentration of chain defects along the chains, the value of δ χ turns out to be a function of crystallinity of the lamellar material.