The effect of weak fields (~0.01 mT.) upon the remanent magnetization of basalts, granodiorites and polycrystalline magnetite during uniaxial compression has been investigated. Samples carrying NRM and AF demagnetized NRM were used. The demagnetized samples showed the largest effects. In the low stress range of less than 100 bars, the influence of stress was demagnetization. In the absence of an applied field, the magnetization rotated away from the compression axis, as is commonly observed. However, with the application of a field of between .01 to .02 mT., the magnetization rotated into alignment with the field as stress was increased. AF demagnetization after the application of 1 kbar of load produced large and repeatable magnetization increases confined to a very narrow coercivity band. AF demagnetization to 10 mT. removed most of the stress induced remanence. These observations are explained in terms of enhanced remanence acquisition in the presence of stress. This reversible effect unblocks soft domain wall sections which can respond to weak applied fields, or to internal demagnetizing fields. ¿ American Geophysical Union 1988