The gnathosoma of Tetranychus urticae has been studied through light microscopy, S.E.M. and T.E.M. From a functional point of view, the study indicates that the chelicerae are a piercing-sucking structure; the interlocked stylets are actively protracted but passively retracted. The pathway of food through the gnathosoma is redescribed accordingly. Comparative morphology reveals severa! new structures unique to Tetranychidae such as the cervical canaliculus and the prelabial and supralabral cavities. Descriptive terminology is standardized with that used for other mites.