The geomagnetic storm-time variation Dst allows information concerning the global distribution of electrical conductivity in the upper mantle to be obtained. Such storm events can be analysed for periods up to 10 days following the storm commencement. The penetration depth of the associated induced currents within the Earth is over 1000km. Global response estimates were derived from storm data analysed by MARSHALL (1980) covering the frequency range 0.07 to 2cpd. The response data were inverted to give conductivity profiles within the upper mantle using the algorithms due to BAILEY (1970a, 1970b), PARKER (1980) and PARKER and WHALER (1981), and FISCHER et al. (1981a). The results obtained from these inversions are consistent, and reveal two major discontinuities in conductivity of several orders of magnitude at depths between 650-750km and 950-1050km. It is also suggested by the results that the uppermost region of the mantle is poorly conducting.