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 de livered position a portion of the dose delivered indicator (109) emerges increasingly from the distal housing end.
