This article analyses the iconography of the clerical liturgical vestments through the study of its codification and regularisation in the Late Middle Ages, laying stress on the importance of understanding ritual apparatus for the correct interpretation of images. Some 12th-and 13th-century written sources, especially the Rationale divinorum officiorum by Guillaume Durand, provide us references to understand the evolution of the ornaments and their symbolism. At the same time, the systematisation of liturgical colours made by Pope Innocent III (1161-1216) in his De sacro altaris mysterio, displays some important facts to interpret the colour evolution of costumes related to the liturgical year and its feasts. Interior ornaments such as the amices, albs, cinctures, rochets or talars can be found in medieval iconography, along with the chasuble, the cope, the dalmatic and the surplice. Clerical insignia (stole and maniple) require a specific attention due to its symbolism in the Late Middle Ages.