Engineering structures of concrete are generally recognized to be rarely fully water-saturated. The water transportation process in unsaturated cementitious materials offers therefore a relevant problem the understanding of which can be crucial in assessing concrete's degradation and failure mechanisms. In recent years, the number of published papers on this topic is significantly increased. This review presents the latest advancements in determining water permeability of unsaturated cement-based materials by experimental methods and numerical modelling. The effects are summarized of water-cement ratio (w/c), curing age, particle size distribution, interfacial transition zone (ITZ) and supplementary cementitious materials (SCMs) on the permeability of partially saturated cement-based materials. Next, the underlying relationship between relative water permeability and pore structure is presented and discussed. Additionally, an insight into water transport mechanism of unsaturated concrete is proposed. Finally, some evaluative conclusions are drawn that can be instrumental for setting up future studies.