The cynodonts, a diversified group of advanced therapsids which appeared in the fossil record at the end of the Permian, constitute an important component of many Triassic and Early Jurassic terrestrial ecosystems. It seems now generally accepted that the cynodonts are the sister-group of the therocephalians, and that they include the mammals as a derived subgroup, but many aspects of their phylogeny still remain a matter of debate. The problem of the relationships of the various families of advanced cynodonts to mammals, in particular, is far from being solved. Progress in the knowledge of the group, though very significant, has also been very unequal: many small forms, in particular, are known up to now only by rare and often incomplete specimens. A better understanding of the group will require more fieldwork and new discoveries. This paper is a short account of studies on the phylogeny of cynodonts; it is an attempt to point out what has already been clearly established, and what remains obscure or controversial.KEY WORDS. Cynodontia. Therapsida. Triassic. Phylogeny.