Remarques generales sur la structure fondamentale du gnathosoma. - The gnathosoma of mites, even of the most primitive species, represents already an extremely specialized structure. In order to understand its phylogeny, the investigation should start from a primitive Arachnid in which the mouth is still situated in front of the chelicerae, and in which the chelicerae are still in front of the palps. This primitive condition is indeed still found in the Palpigradida. The mouthparts of a species of this group (Eitkoenenia mirabilis) have been studied; they serve as starting point for an investigation of the fondamental structure of the gnathosoma of mites. The displacement of several parts of the gnathosoma in comparison with the primitive position has been studied, and phylogenetic interpretations have been added. Special attention has been paid to the displacement, in the course of phylogeny, of (1) the cheliceral frame with the tegulum and the coxal regions of the chelicerae, (2) the mouth with the lips, (3) the cervix, and (4) the palp and the ventral surface of the infracapitulum.