A pulmonary dosing system and method for supplying to a patient a predetermined amount of respirable therapeutically active material. The system comprises a patient interface to introduce the material into the patient's lungs. The patient interface is connected to a flexible inhalation tube (4) and a flexible exhalation tube (5). The exhalation tube (5) is connected to a filter (25) having an outlet connected to atmosphere. The inhalation tube (4) is connected to an apparatus for providing pulsed amounts of the material entrained in filtered atmospheric air. A control unit (8) operates the pulmonary dosing system in accordance with operator inputs regarding the number of patent exhales between pulses, and pulse length. The exhaust filter (25) and the apparatus for providing pulsed amounts of the therapeutically active material may be enclosed in a containment case (7) and the patient's interface may comprise a mouth tube-mask (1, 2) combination when the therapeutically active material comprises at least one toxic drug.
