Described is a sheath removal mechanism (1) for removing a protective needle sheath (2) from an injection needle (3) of a syringe (4) in a drug delivery device (5). The sheath removal mechanism (1) comprises a cap (6) adapted to cover a distal end of a drug delivery device (5) and adapted to engage the protective needle sheath (2), and at least one rotatable cam (7) adapted to move the cap (6) in a distal direction (D) away from the syringe (4) when rotated from a first rotational position (P1) towards a second rotational position (P2).