Magnetoresistive devices (based on, for example, magnetic multilayers(1)) exhibit large changes in electrical resistance in response to a magnetic field, which has led to dramatic improvements in the data density and reading speed of magnetic recording systems. Manganese oxides having a perovskite structure (the so-called manganites) can exhibit a magnetoresistive response that is many orders of magnitude larger than that found for other materials, and there is therefore hope that these compounds might similarly be exploited for recording applications(2-11). Here we show that the switching of resistive states in the manganites can be achieved not only by a magnetic field, but also by an electric field. For manganites of the form Pr1-xCaxMnO3, we iind that an electrical current (and by implication a static electric held) triggers the collapse of the low-temperature, electrically insulating charge-ordered state to a metallic ferromagnetic state. We suggest that such a phenomenon could be exploited to pattern conducting ferromagnetic domains within an insulating antiferromagnetic matrix, and so provide a route for fabricating micrometre- or nanometre-scale electromagnets.