Anomalous galvanomagnetic effects associated with spatial discontinuities in carrier concentration have been observed inn‐type InSb. These discontinuities result from anisotropic segregation of impurities during crystal growth. An increase in the magnitude of the Hall coefficient at 20 000 gauss to nearly twice the weakfield value was observed in one case. The magnetoresistance is especially sensitive to inhomogeneities. For an inhomogeneous sample at a particular magnetic field, the measured &Dgr;&rgr;/&rgr;0may be as much as 100 times larger than that for a homogeneous sample. Negative magnetoresistance has also been observed at room temperature in inhomogeneous samples. All of the above observations are predicted qualitatively by considering a simple model consisting of a long, thin specimen having a discontinuity in resistivity and Hall coefficient in the current direction. The boundary value problem corresponding to this case is solved to predict the electric field and current densities.