A diluent/medication mixing syringe assembly is described which includes a cannula which extends through a syringe plunger assembly into a reservoir of the syringe assembly. The cannula facilitates injection of a diluent, medication or other fluid into the fluid reservoir of the syringe assembly immediately prior to use for mixing with a medication in the reservoir. In one embodiment, a mixing element is secured to a distal end of the cannula within the reservoir to improve mixing efficiency.