An inhaler for dispensing medicament in the form of a dry powder is powder is provided with an airway (50) through which a dose travels from an ejection zone to an outlet of the airway. The airway (50) has an inlet means which is so arranged as to create a jacket of air, flowing through a part of the airway extending from the ejection zone to the outlet. The jacket of air surrounds said dose and thereby prevents it form impinging on the airway walls. This reduces accumulation of material on the airway walls, and thus improves the consistency of performance of the inhaler. Preferably, the inlet means includes a throat for producing a stream of fast flowing air which creates a zone of low pressure in front of the ejection zone, thereby to facilitate ejection of a dose.