The fluid amplifier provides a solution for certain design problems associated with modern military medicine. The Military requires its medical equipment to possess not only a reliability and life compatible with its proposed use, but sufficient ruggedness to withstand the rigors of logistics and operation in the field. Where fluid amplifiers are used, these requirements are generously satisfied. By reducing the number of moving parts involved, logistics problems are simplified and manufacturing costs reduced. In illustration, this paper describes a volume limited respirator, a pressure cycled respirator, an external cardiac compressor, and a blood pump all utilizing fluid amplifiers for control and designed primarily for Army medicine.