The effect of an external stress on the barrier properties of natural, bromobutyl, and nitrile rubber were studied using a modified ASTM permeation method. Stress-induced changes such as a decrease in the breakthrough time with mechanical elongation was observed. Upon application of a small mechanical deformation, little change was observed in terms of steady-state permeation Aux. On the other hand, a stress-enhanced diffusion was observed for most of the solvent/rubber pairs studied.