The present invention deals with an auto-disable syringe comprising of a barrel, a needle holder within the barrel, a cap mounted on the first end of the barrel to protect the needle mounted to the needle holder, a plunger, a plunger extension with a frangible portion to enable the plunger extension to be disabled after the withdrawal of the needle into the barrel. The needle holder is located adjacent to the first end of the barrel, said needle holder being configured to hold a needle extending from a first end. The plunger located within the barrel such that it forms a seal with an inside surface of the barrel to enable the plunger to force fluid from the barrel via a needle as the plunger is pushed towards the first end of the barrel in use. The plunger also includes a locking arrangement that is configured to cooperate with locking arrangement of the needle holder to lock the plunger to the needle holder. The plunger extension, located within the barrel behind the plunger, enables the plunger to be pushed towards the first end of the barrel by applying a pushing force to the plunger extension .The plunger extension includes a locking arrangement that is configured to cooperate with the second locking arrangement of the plunger to lock the plunger extension to the plunger
