The present invention is generally directed to an assembly for a drug delivery device comprising a first threaded member (50, 50'), a second threaded member (40, 60') with a longitudinal axis and a thread (61), having at least two consecutive portions (62, 63, 64) with different leads. The first threaded member (50, 50') and the second threaded member (40, 60') are adapted and arranged to rotate with respect to one another about the longitudinal axis of the second threaded member (40, 60') during dose setting operation of the assembly, the first threaded member (50, 50') thereby being axially displaced along the second threaded member (40, 60') from a start position to an end position with respect to the second threaded member (40, 60') due to the mechanical cooperation of the first threaded member (50, 50') with the thread (61). According to the invention, a fast portion (62, 64) of the thread (61), having a greater lead than a slow portion (63) of the thread (61), comprises a multi-start thread and the slow portion (63) comprises less starts than the fast portion (62, 64). The invention is further directed to a drug delivery device for setting and dispensing a number of user variable doses of a medicament comprising such an assembly.La présente invention concerne de manière générale un ensemble pour un dispositif d'administration de médicament comprenant un premier élément fileté (50, 50'), un second élément fileté (40, 60') comprenant un axe longitudinal et un filetage (61), ayant au moins deux parties consécutives (62, 63, 64) comportant différents fils. Le premier élément fileté (50, 50') et le second élément fileté (40, 60') sont conçus et agencés pour tourner l'un par rapport à l'autre autour de l'axe longitudinal du second élément fileté (40, 60') pendant une opération de réglage de dose de l'ensemble, le premier élément fileté (50, 50') étant ainsi déplacé axialement le long du second élément fileté (40, 60') d'une position de départ à une position de fin p
