A bedside-pharmacy systen for the preparation and delivery of intravenous drugs. The system includes a liquid inlet for connection to a liquid supply, vial receptacles, and a liquid outlet for providing the intravenous drug in mixed, liquid form to the patient. The system may include a chamber having a variable volume, and a valve mechanism, which may be actuated to control flow between the liquid outlet, the variable-volume chamber, the vial receptacles and the liquid inlet. The system induces change in the volume of the variable-volume chamber and actuates the valve mechanism, so as to introduce liquid from the liquid inlet into the vials and reconstitute or dilute the drugs and so as to deliver the drugs to the patient. In a preferred embodiment, the liquid inlet, the vial receptacles, the variable-volume chamber, the liquid outlet and the valve mechanism (in other words, all components that come into contact with the liquid) are located in a disposable cassette, which may be received in a control unit. The system may include means for changing the chamber volume and actuating the valves so as to move the liquid repeatedly between a vial and the chamber. After the drug has been reconstituted, the system may cause the drug to be further diluted by providing an additional volume of liquid to be mixed with the drug. The system may further include a second chamber for delivery of the drug to the patient in precise quantities.