The unique colour patterns of the hermit crab species inhabiting the Iberian Peninsula and geographically close areas are studied based on colour patterns observed in live specimens either in the field or live in the laboratory. Live colour patterns are shown to be useful for differentiating species in the Paguroidea from Iberian waters. Colour information has not been frequently documented in previous studies, mainly because of difficulties in accessing live specimens. Up to 51 species are currently recorded within the study area, 45 of which are included in the present work, focusing on the distinctive colour traits for each species that can be observed in the field. A complete key for identifying the species within the study area based on colour patterns is included. This study is the first attempt to put in place this type of tool oriented to field work. Further studies will be required to complete and update this information, especially for species which are scarce or difficult to observe alive.