It is shown theoretically and experimentally that the current density is not uniform in the neighborhood of a 180 ° domain wall, in a pure ferromagnet traversed by an electric current at low temperature. The effect is caused by the abrupt reversal of the internal fieldB=Msacross the wall, and by the corresponding gradual reversal of the Hall electric field. In a noncompensated ferromagnetic metal (Co, Ni) in the high field limit&ohgr;c&tgr;≫1, domain walls would act as if they were electrically insulating; the current could cross the wall only through a small ``hole'' located at one end of the wall, creating an infinite current density there. A cobalt single crystal of limited purity (R300/R4.2= 65) was cut in the shape of a thin slab normal to thecaxis. One‐half of the slab is magnetized to saturation in thecdirection and the other half is magnetized in the opposite direction, thus simulating one domain wall. When a dc current crosses the wall, the current density is found to be larger at one end of the wall than at the other end in a ratio of 1.7, in agreement with predictions. Current density is monitored locally with pairs of voltage probes. The magnitude and sign of the effect is consistent with &ohgr;c&tgr; = 0.18 and electronlike carriers.