A mini review of the topic of deformation bands is presented in the paper. The concept of deformation bands is defined and their impact on the flow of fluids in porous sedimentary rocks is determined. Deformation bands are mm-thick low-displacement deformation zones which have intensified cohesion and lower permeability compared with ordinary fractures. This term was introduced in 1968 in material science, ten years later it appeared in the geological context. This microstructures can occur as barriers or migration pathways for hydrocarbons. Their role depends mainly on microstructural features, and they are also considered in reservoir modeling. The occurrence of deformation bands in Poland is also outlined and discussed - they have been described in Western Outer Carpathians (Magura and Silesia nappes).