Ionic liquids are highly polar solvents with negligible vapour pressure and low flammability that offer a potentially "green" alternative to volatile organic compounds (VOCs). However in order to confidently label this class of solvents as "green", their affect on the environment must be thoroughly examined. As a result various toxicity, ecotoxicity and biodegradation studies have been carried out on ionic liquids. Although toxicity evaluations of ionic liquids have been widely reported in the literature, biodegradation data are comparatively scarce. In this tutorial review we present an overview of studies into the biodegradability of ionic liquids, including the various methods of biodegradation assessment, trends observed for structurally related ionic liquids, and applications of biodegradable ionic liquids in synthetic chemistry.