An electronically-controlled positive-displacement bellows-type air pump has been developed in the Bio-medical Engineering Laboratory for the treatment of adult Sleep Apnea Syndrome (SAS). An electronically-controlled positive-displacement pump has been employed in order to eliminate the pressure regulator and accompanying noise of present therapeutic devices. The positive-displacement pump is found to quietly and effectively provide the required airway pressures for the treatment of adult Sleep Apnea Syndrome. New developments in the reduction of the size and noise levels of current therapeutic devices, however, preclude mass production of the bellows-type pump because of its size disadvantage. The custom nasal mask and exhalation valve, control system, pressure-monitoring alarm system, and the controlled humidifier of the positive-displacement pump should be incorporated within the present fanâ type Nasal Continuous Positive Airway Pressure (NCPAP) system to provide quieter, more comfortable, and safer NCPAP therapy. Before the design and development of the positive displacement NCPAP pump is detailed in this thesis, however, the problem of adult Sleep Apnea Syndrome is introduced, available therapies are investigated, and the current NCPAP therapy system is examined. / Master of Science