A drive assembly for a drug delivery device is presented having a housing with a proximal end and a distal end, a drive member, and a piston rod. A longitudinal axis extends between the proximal end and the distal end and the piston rod is axially moveable relative to the housing. The piston rod has a guide track and the drive member has a guide piece disposed and movable in the guide track. The guide track is configured with at least one section which is oblique relative to the longitudinal axis and defines a displacement for dispensing a single pre-set dose of medication during a relative movement between the guide piece and the piston rod when the guide piece cooperates with the oblique section between a distal final area of the oblique section and a proximal final area of the oblique section.