 Microwave, MW, heating differs from conventional heating in the way heat is transferred, while MW treatment can modify natural fibres, NF, making them useful for developing polymeric biocomposites, biofuels, activated carbon and carbon nanostructures. This review summarizes advances of MW radiation treatment on NF, and assesses the relationship between MW reactor design, processing conditions, and dielectric properties of each fibre component. An overview of morphological and structural changes of NF after MW treatment is presented to suggest processing, methodologies for increasing reproducibility, functionality, applications, and industrial process scale-up. This article was authored by G. Y. Romero-Zuniga, P. Gonzales-Morrones, S. Sanchez-Valdes, and others.