Abstract: An improved breath coordinated inhaler is provided for administering medication to a patient in aerosol form for respiratory inhalation therapy. The improved inhaler comprises a compact housing adapted to receive and support a medication cannister including a valve assembly actuatable to deliver a dosage of the medication in aerosol form. The housing includes a plunger mounted at a first end thereof for displacing the cannister against a spray nozzle located at a second end of the housing to actuate the valve assembly and deliver the medication through a mouthpiece to the patient. The plunger is associated with a seal arrangement for venting the housing when the plunger is depressed to allow the patient to draw in air in timed relation to the medication delivery, and to substantially re-seal the housing against ingress of contaminants when the plunger is released.