A powder inhalation device comprising a housing containing a pharmacologically active compound, a conduit (8) with an outlet extending into the housing through which a user can inhale to create an airflow through the conduit, a dosing unit (6, 7) for delivering a dose of the compound to the conduit and baffles (9) arranged within the said conduit to aid disintegration of powder agglomerates entrained in said airflow. The baffles (9) comprise a plurality of staggered plates extending into the conduit from opposite sides of the conduit at an angle of less than 90° to the sides of the conduit and are inclined towards the outlet to create a plurality of constrictions within the conduit and a plurality of changes in the direction of the said airflow through the conduit.