An inhaler for inhaling pulverulent medicament from within a capsule comprises a chamber 24 within which the capsule is free to rotate while having its longitudinal axis in the median plane of the chamber and thus generally parallel to the front and rear walls 29 and 30 of the chamber, by virtue of the fact that the spacing between said front and rear walls is less than the axial length of the capsule but just greater than the diameter of the capsule. The device includes pins 21 serving as opening means to pierce the ends of the capsule while it is seated in a recess 25, whereupon the retraction of the pins 21 allows the capsule to be entrained into swirling airflow in the chamber 24 during inhalation of air through air inlets 26 and out through a mouthpiece nozzle 27.