The invention refers to an auto-injector (1) for administering a dose of a liquid medicament (M), the auto-injector (1) having a distal end (P) and a proximal end (D) with an orifice intended to be applied against an injection site and 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), wherein the syringe (3) is slidably arranged with respect to the housing (2), - a drive means (8) capable of, upon activation: - pushing the needle (4) from a retracted position into an advanced position through the orifice and past the proximal end (P), and - operating the syringe (4) to supply the dose of medicament (M), - a plunger (9) for transmitting power from the drive means (8) to the syringe (3) and/or stopper (6), - activating means arranged to lock the drive means (8) in a compressed state prior to manual operation and capable of, upon manual operation, releasing the drive means (8) for injection, characterized in that translation of the needle (4) and the syringe (3) and/or translation of the plunger (9) in longitudinal direction is controlled by at least one ramp (2.5, 9.6, 2.7, 7.2) or one thread so as to cause the syringe (3) and/or the plunger (9) to rotate when translated at least during part of the translation.L'invention concerne un auto-injecteur (1) pour administrer une dose d'un médicament liquide (M), présentant une extrémité distale (P) et une extrémité proximale (D), comprenant un orifice à appliquer contre un site d'injection. L'auto-injecteur comporte un boîtier allongé (2) conçu pour contenir une seringue (3) pourvue d'une aiguille creuse (4) et d'un bouchon (6) pour boucher la seringue (3) et déplacer le médicament (M), la seringue (3) étant logée coulissante par rapport au boîtier (2)； un élément d'entraînement (8) capable, en cas d'actionnement, de pousser l'aiguille (4) d'une position rétractée vers une position av
