Auto-injector for administering a dose of a liquid medicament, comprising: - an elongate housing arranged to contain a syringe with a hollow needle and a stopper for sealing the syringe and displacing the medicament, the housing having a distal end and a proximal end with an orifice intended to be applied against an injection site, wherein the syringe is slidably arranged with respect to the housing, - spring means capable of, upon activation: - pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end, - operating the syringe to supply the dose of medicament, and - retracting the syringe with the needle into the covered position after delivering the medicament, - activating means arranged to lock the spring means in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring means for injection, wherein the spring means is a single drive spring in the shape of a compression spring arranged to be grounded at a distal end in the housing for advancing the needle and for injecting the dose of medicament via a plunger and wherein the drive spring is arranged to have its ground in the housing switched to its proximal end for retracting the syringe, wherein an interlock sleeve is telescoped in the proximal end of the housing, the interlock sleeve translatable in longitudinal direction between a proximal position and a distal position and biased in proximal direction in a manner to protrude from the housing in the proximal position, wherein the activating means comprises a trigger button arranged at the distal end of the auto-injector, wherein the trigger button is locked, thereby preventing actuation when the interlock sleeve is in its proximal position in an as delivered state and wherein translation of the interlock sleeve unlocks the trigger button so as to allow actuation, wherein in the as delivered state the interlock sleeve is coupled to the plunger for joint axial translation, wherein a distal end of the plunger is arranged to interact with the trigger button in a manner to lock and/or unlock it, characterized in that a tubular syringe carrier is arranged for holding the syringe and supporting it at its proximal end, the syringe and the syringe carrier arranged for joint axial translation, wherein the syringe carrier is telescoped in the interlock sleeve, wherein in its proximal position the interlock sleeve is arranged to be coupled to the syringe carrier for joint axial movement in the syringe's retracted position so that the syringe and needle cannot advance and the needle remains in its covered position and wherein the interlock sleeve in its distal position is arranged to allow decoupling of the syringe carrier, wherein the decoupling occurs upon release of the drive spring and the resulting translation of the syringe carrier, syringe and needle in proximal direction into the needle's advanced position for piercing a patient's skin with the interlock sleeve being held in distal position by the injection site. - an elongate housing arranged to contain a syringe with a hollow needle and a stopper for sealing the syringe and displacing the medicament, the housing having a distal end and a proximal end with an orifice intended to be applied against an injection site, wherein the syringe is slidably arranged with respect to the housing, - spring means capable of, upon activation: - pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end, - operating the syringe to supply the dose of medicament, and - retracting the syringe with the needle into the covered position after delivering the medicament, - pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end, - operating the syringe to supply the dose of medicament, and - retracting the syringe with the needle into the covered position after delivering the medicament, - activating means arranged to lock the spring means in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring means for injection,