The influence of domain walls on transport properties of ferromagnetic materials is analyzed theoretically and the results are compared with recent experiments. In the case of diffusive transport through a thick domain wall, the semiclassical approximation is applied and a local spin transformation is performed, which replaces the system with a domain wall by the corresponding system without domain wall but with an additional gauge field. Due to a redistribution of single-particle electron states at the wall, one obtains either negative or positive contributions to resistivity. On the other hand, suppression of the weak localization corrections to conductivity by the gauge field created by the wall leads to an increase in the low-temperature conductivity in the presence of the domain wall. In the case of narrow domain walls the semiclassical approximation is not valid. Instead of this one can use an approach based on scattering matrix. In this particular case, the domain wall induces a large positive contribution to the resistivity. The corresponding magentoresistance in nanostructures with sharp domain walls can be large, in accordance with recent experiments.