The present invention concerns a dosing unit for an injection device (100) and an injection device incorporating the dosing unit. The dosing unit comprises a housing (102) extending along a longitudinal axis from a proximal housing end to a distal housing end, the distal housing end being adapted for connection with a variable volume reservoir, an injection mechanism for expelling a dose of a substance held in a connected variable volume reservoir, the injection mechanism being arranged at least partially in the housing (102) and comprising an injection button (157), a dose defining structure (140) configured to move from a start position to an end-of-dose position in response to a dose expelling operation of the injection button (157), and a piston rod (160) configured to move in a dose delivery direction from a first position to a second position in response to a movement of the dose defining structure (140) from the start position to the end-of-dose position, and a dose delivered indicator (109) configured to move axially in a distal direction from a dose ready position to a dose delivered position in response to the movement of the dose defining structure (140) from the start position to the end-of-dose position, wherein during movement from the dose ready position to the dose delivered position a portion of the dose delivered indicator (109) emerges increasingly from the distal housing end.La présente invention concerne une unité dadministration pour un dispositif dinjection (100) et un dispositif dinjection incorporant lunité dadministration. Lunité dadministration comprend un boîtier (102) sétendant le long dun axe longitudinal dune extrémité de boîtier proximale à une extrémité de boîtier distale, lextrémité de boîtier distale étant adaptée pour raccordement à un réservoir à volume variable, un mécanisme dinjection pour expulser une dose dune substance contenue dans un réservoir à volume variable raccordé, le mécanisme dinjection étant agencé au moins partie
