An injection device comprises 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 is 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 is adapted to receive a vial containing fluid and connect it to the discharge nozzle. There is also 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.
