Modifications in the design of the conventional syringe are disclosed, for constructing dual substance prefilled mixing syringe. Total storage volume is extended by utilizing plunger body inner compartment (2). Vacuum activated valve (3), moulded as part of the plunger is assuring one-way flow. The process of aspiration and mixing is simplified to one-step procedure, driven by the vacuum created upon plunger withdrawal. With the prefilled mixing syringe embodiment, exact mixing dosage of the substances is achieved, and the time for solution preparation is significantly reduced.
