We evaluated five portable volume ventilators from four manufacturers. Ventilation requirements in general patient care areas in the hospital differ from those for home care; therefore, we considered use of the units for these applications separately. None of the units was ideal for either application because of the limitations and risks of each ventilator. All units were rated Conditionally Acceptable, but were ranked for hospital use only. The primary conditions for acceptable hospital use were that exhaled-volume monitoring be performed for all patients and that O2 monitoring be performed both when setting FIO2 and continuously when FIO2 levels are critical. For home care, users should carefully weigh the advantages and disadvantages of each unit and base their choice of a unit primarily on individual patient needs, ease of use, and safety factors.