An autoinjector comprising a housing in which can be mounted a syringe comprising: a barrel for holding a volume of medicament, a needle at one end of the barrel in fluid communication with the medicament, a plunger axially-moveable in the barrel to a forwardmost position; a needle sheath which is capable of sealing the forwardmost end of the needle to maintain sterility of the medicament within the barrel whereby, in use, the needle sheath must be removed from the needle immediately prior to actuating the autoinjector; and a removable needle cover for containing the needle sheath; the autoinjector comprising: a syringe support means (100, 100') for supporting the barrel of the syringe at an axial location at or forward of the forwardmost position of the plunger of the syringe, the syringe support means (100, 100') providing a reaction surface (109, 109') for a front shoulder of the barrel or a narrowed cone region of the syringe where the needle is attached; characterised in that said syringe support means (100, 100') comprises an intermediate portion and a front portion which together include radially spaced slots that define a plurality of radially flexible fingers (108, 108'), the plurality of radially flexible fingers (108, 108') comprising one or more inwardly-directed protrusions which form said reaction surface, wherein the reaction surface (109, 109') is configured to provide an axial compressive force on the barrel of the syringe when a forward axial force is applied to the plunger of the syringe, and wherein when the syringe is inserted into the syringe support means (100, 100'), the radially flexible fingers (108, 108') flex radially outward from a normal position as a needle cover passes and then spring back to their normal position. a barrel for holding a volume of medicament, a needle at one end of the barrel in fluid communication with the medicament, a plunger axially-moveable in the barrel to a forwardmost position; a needle sheath which is capable of sealing the forwardmost end of the needle to maintain sterility of the medicament within the barrel whereby, in use, the needle sheath must be removed from the needle immediately prior to actuating the autoinjector; and a removable needle cover for containing the needle sheath; the autoinjector comprising: a syringe support means (100, 100') for supporting the barrel of the syringe at an axial location at or forward of the forwardmost position of the plunger of the syringe, the syringe support means (100, 100') providing a reaction surface (109, 109') for a front shoulder of the barrel or a narrowed cone region of the syringe where the needle is attached; characterised in that said syringe support means (100, 100') comprises an intermediate portion and a front portion which together include radially spaced slots that define a plurality of radially flexible fingers (108, 108'), the plurality of radially flexible fingers (108, 108') comprising one or more inwardly-directed protrusions which form said reaction surface, wherein the reaction surface (109, 109') is configured to provide an axial compressive force on the barrel of the syringe when a forward axial force is applied to the plunger of the syringe, and wherein when the syringe is inserted into the syringe support means (100, 100'), the radially flexible fingers (108, 108') flex radially outward from a normal position as a needle cover passes and then spring back to their normal position. a syringe support means (100, 100') for supporting the barrel of the syringe at an axial location at or forward of the forwardmost position of the plunger of the syringe, the syringe support means (100, 100') providing a reaction surface (109, 109') for a front shoulder of the barrel or a narrowed cone region of the syringe where the needle is attached; characterised in that said syringe support means (100, 100') comprises an intermediate portion and a front portion which together include radially spaced slots that define a plurality of radially flexible fingers (108, 108'), the plurality of radially flexible fingers (108, 108') comprising one or more inwardly-directed protrusions which form said reaction surface, wherein the reaction surface (109, 109') is configured to provide an axial compressive force on the barrel of the syringe when a forward axial force is applied to the plunger of the syringe, and wherein when the syringe is inserted into the syringe support means (100, 100'), the radially flexible fingers (108, 108') flex radially outward from a normal position as a needle cover passes and then spring back to their normal position.