Abstract. This review is devoted to presentation and analysis of physical mechanisms of ohmic contacts formation in semiconductors. In addition to the classical mechanisms known for decades, new mechanisms for current flow in ohmic contacts researched for the recent decade are described. Used in this review were the original results of the authors, which they described earlier in various papers of recent years. Current flow through dislocations combined with metal shunts, realized, in particular, on the lapped semiconductor surface; detailed current flow mechanism in the presence of doping step and current flow through the heavily doped semiconductor surface charge states reduction should be noted among the new mechanisms of current flow. These current flow mechanisms are characterized by the presence of specific contact resistance growth with temperature increase in some temperature intervals and contacts ohmicity up to helium temperatures.