The invention relates to an auto-injector (1) for administering a dose of a liquid medicament (M), comprising: - an elongate housing (2) arranged to contain a syringe (3) with a hollow needle (4) and a stopper (6) for sealing the syringe (3) and displacing the medicament (M), the housing (2) having a distal end (D) and a proximal end (P) with an orifice intended to be applied against an injection site, wherein the syringe (3) is slidably arranged with respect to the housing (2), - spring means (8) capable of, upon activation: - pushing the needle (4) from a covered position inside the housing (2) into an advanced position through the orifice and past the proximal end (P), - operating the syringe (3) to supply the dose of medicament (M), and - retracting the syringe (3) with the needle (4) into the covered position after delivering the medicament (M), - activating means (20) arranged to lock the spring means (8) in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring means (8) for injection. The spring means (8) is a single drive spring (8) arranged to be grounded at a distal end (8.1) in the housing (2) for advancing the needle (4) and for injecting the dose of medicament (M) via a plunger (9) and wherein the drive spring (8) is arranged to have its ground in the housing (2) switched to its proximal end (8.2) for retracting the syringe (3). An interlock sleeve (25) is telescoped in the proximal (P) end of the housing (2), the interlock sleeve (25) translatable in longitudinal direction between a proximal position and a distal position, wherein in its proximal position the interlock sleeve (25) is arranged to be coupled to the syringe (3) in the syringe's retracted position and wherein the interlock sleeve (25) in its distal position is arranged to allow decoupling of the syringe (3).
