An auto-injector comprising: a housing adapted to receive a fluid container having a discharge nozzle and a dispensing piston moveable in the fluid container to expel the contents of the fluid container out of the discharge nozzle; a drive adapted on activation to act on the fluid container to advance it from a retracted position in which the discharge nozzle is contained within the housing to an extended position in which the discharge nozzle extends from the housing and act on the dispensing piston to expel the contents of the fluid container out of the discharge nozzle; a connector adapted to receive a vial (300; 400) containing fluid and connect it to the discharge nozzle; and means to move the dispensing piston relative to the fluid container from a first position in which the dispensing piston is located in the fluid container adjacent the discharge nozzle to a second position in which the dispensing piston has been drawn away from the discharge nozzle, thereby drawing fluid from the vial into the fluid container, and characterised in that the connector is a removable cap (101; 401) located over the discharge nozzle on the auto-injector, wherein the cap has an open end (101c; 401c) which is adapted to receive the vial, wherein the removable cap is adapted such that removal of the cap from the housing detaches the vial from the discharge nozzle, wherein the removable cap comprises a removable cover element (101b; 401b) over the open end, wherein the removable cover element is adapted to be removed prior to insertion of a vial into the open end, wherein the removable cover element holds a shield which is located over the discharge nozzle when the removable cover element is in place on the removable cap and which is removed from the discharge nozzle when the removable cover element is removed from the removable cap. a housing adapted to receive a fluid container having a discharge nozzle and a dispensing piston moveable in the fluid container to expel the contents of the fluid container out of the discharge nozzle; a drive adapted on activation to act on the fluid container to advance it from a retracted position in which the discharge nozzle is contained within the housing to an extended position in which the discharge nozzle extends from the housing and act on the dispensing piston to expel the contents of the fluid container out of the discharge nozzle; a connector adapted to receive a vial (300; 400) containing fluid and connect it to the discharge nozzle; and means to move the dispensing piston relative to the fluid container from a first position in which the dispensing piston is located in the fluid container adjacent the discharge nozzle to a second position in which the dispensing piston has been drawn away from the discharge nozzle, thereby drawing fluid from the vial into the fluid container, and characterised in that the connector is a removable cap (101; 401) located over the discharge nozzle on the auto-injector, wherein the cap has an open end (101c; 401c) which is adapted to receive the vial, wherein the removable cap is adapted such that removal of the cap from the housing detaches the vial from the discharge nozzle, wherein the removable cap comprises a removable cover element (101b; 401b) over the open end, wherein the removable cover element is adapted to be removed prior to insertion of a vial into the open end, wherein the removable cover element holds a shield which is located over the discharge nozzle when the removable cover element is in place on the removable cap and which is removed from the discharge nozzle when the removable cover element is removed from the removable cap.