INTRODUCTION: The concept of a critical care capability in space implies the ability to deliver appropriate intravenous fluids to an ill or injured crew member. Mass and volume constraints preclude carrying sufficient quantities of the various solutions necessary for a 45 day support period. Investigations were undertaken to develop a system for preparation of solutions on-orbit for medical use. Further studies have investigated mechanisms of delivery of the intravenous infusion to a patient. MATERIALS AND METHODS: Fluid production is the result of several development contracts. Hardware was evaluated to determine their suitability to produce sterile water for injection, and parenteral solutions as described in the United states Pharmacopeia, Volume XXI. Testing was designed to determine the limits of the devices. Evaluations of candidate intravenous infusion pumps were undertaken in the laboratory to characterize the devices. RESULTS: Initial characterizations of the sterile water production hardware indicate its ability to function beyond the desired design limits. Evaluations of the IV solution production hardware have demonstrated its ability to satisfactorily mix a concentrate without external interaction to produce a sterile solution. The candidate IV pump has performed within 10% of stated rates and volumes in microgravity and in unusual configurations in earth-based testing. CONCLUSIONS: Candidate hardware has been developed and initially evaluated for potential use in the Space Station Freedom Health Maintenance Facility Fluid Therapy System. Further testing, including experiments on the Space Shuttle and in Spacelab are scheduled to further test the hardware and the premises on which it was selected.