A preliminary detailed list of the conodonts from the Fromelennes Formation is established. This formation is subdivided into three members. At three levels faunal changes are clear enough to characterize important biostratigraphic boundaries. Polygnathus rhenanus, P. dubius and leriodus eslaensis latecarinatus n. subsp. characterize the first level, Spatbognathodus insitus and Schmidtognatbus hermanni the second, and Ancyrodella rotundiloba the third. Only the last two levels are taken into account in defining the boundary between the Givetian and the Frasnian and between the Middle and Upper Devonian. The new subspecies, Icriodus eslaensis latecarinatus, is fully described. Diagrams of other important species and subspecies relevant to the problem are given and they are briefly discussed