A syringe comprises a barrel with a plunger in slidable and sealing engagement therein, and a needle attached to one end of the barrel. The barrel has an aspiration device in the form of manually-operable resilient portions, which can be operated to cause a pressure differential in the barrel, the pressure differential then being used to perform aspiration. The resilient portions are preferably formed by localized reductions of wall thickness in the external surface of the barrel.