The following historical review of orchil dyes represents a collation of the scattered data on this subject. The principal aim has been to survey the information on these particular lichen dyes relating it to their varied usage in the textile trades through the ages. A summary of their methods of manufacture and application is also appended. The term orchil was introduced into England, probably during the fourteenth century, to denote the dye specifically made from several species of Roccella that was first manufactured in Florence and known there as oricello. Latterly this name became corrupted to describe all purple and red dyes made from a wide range of lichens, many of which also had vernacular and trade names. The first section of the paper outlines a general historical survey; the following two sections deal with the methods of preparing orchil as, practised at different times, the purposes for which it was employed, and its application in dyeing.