This paper provides a survey of the ways in which Greek words and word roots have been used in the nomenclature of prokaryotes and explores the extent to which the different uses agree with the wording of the International Code of Nomenclature of Prokaryotes. We here give recommendations on how to use Greek words and word roots in new genus names and specific epithets so that the resulting names are in agreement both with the rules of Greek grammar and with Principle 3 of the Code.