The permeability and diffusivity of permanent gases have been reported for coextruded linear low-density polyethylene (LLDPE) films. Results suggest that the gas permeation in coextruded LLDPE films is a rather complex process. The study on the temperature dependence of the gas transport properties indicates that the melting and crystallization processes, which take place in the films at temperatures above room temperature, strongly affect the permeability and diffusion coefficients of gases through the LLDPE films. In addition, the interpretation of the mechanical relaxation spectra, which presents an α-relaxation in the temperature interval over which the permeation experiments were performed, permits to relate the changes occurring in the spectra with those observed in the permeability measurements. Finally, we have investigated the diffusional characteristics of LLDPE films which were oriented by tensile drawing, either in the longitudinal or transverse directions to the processing orientation. It is observed that drawing of LLDPE films produces an improvement in diffusivity of gases in the films, regardless the orientation given by tensile drawing, whereas the gas permeability through the films exhibits minor changes. The maintenance of permeability properties of coextruded LLDPE under drawing, permits its use as an excellent gas barrier material in the packaging industry.