The effect of stress on the rate of liquid lithium penetration of Armco iron grain boundaries has been determined over a temperature range of 838 to 965 K. The rate of liquid lithium penetration of the Armco iron grain boundary was found to increase with increasing stress for a stress range of 12 to 28 MPa. Specimens stressed to only 12 MPa experienced as much as fifty times the penetration rate of similarly unstressed specimens. The penetration distance has been found to be a single-valued function of creep strain for various combinations of time, temperature, and stress. This relationship of total penetration to total creep strain suggests that the role of stress may be to produce creep strain that ruptures a protective film at the surface, allowing the corrosion rate to proceed at an accelerated rate.