Abstract: Two-chamber syringes for mixing a powdered medicament with a diluent and then injecting the mixed ingredients into a patient are disclosed, together with a technique for assembling those syringes. According to one aspect of the invention, the syringe includes a vial formed with a single glass cylinder closed at one end by a plunger and at its other end by a pierceable diaphragm. An intermediate pierceable diaphragm divides the cylinder into upper and lower chambers, and is locked against axial movement relative to the cylinder. A powdered medicament is provided in the upper chamber and a diluent is provided in the lower chamber. The ingredients are mixed by inserting the vial into a cup-shaped holder having a hollow, pointed needle extending from the base of the holder.