Negative magnetoresistance in hopping regime is sometimes order of magnitude larger than in the metallic regime. I will discuss orbital interference mechanisms of the magnetoresiatnce and will show that magnetic filed dependence of localization length in the strongly localized regime is the universal. The reason for the universality is that the problem of the electron tunneling in a random media belongs to the same universality class as directed polymer problem even in the case of wave functions of random sign. I will also discuss a spin mechanism for negative isotropic magnetoresistance in the hopping regime which results from a memory effect encrypted into spin correlations that are not taken into account by the conventional theory of hopping conductivity. Finally I will discuss a possible relation of the latter mechanism to the magnetic field dependence of room temperature chemical reaction rates.
