A breath actuated dry powder inhaler with a single air circulation chamber for de-agglomeration of entrained powdered medicament using the energy of the inspiratory air stream. The chamber has a substantially polygonal sidewall, a plurality of air supply channels entering the chamber substantially tangentially to its sidewall. A powder channel extends through a powder dose supply region of the inhaler tangentially into the chamber. An air outlet axially extends from a discharge and connects to a discharge channel that extends to a mouthpiece. The polygonal sidewall comprises at least six straight line segments, each straight line segments being spaced at the same first distance from an adjacent one forming the plurality of air supply channels. The air supply channels have the same width. The powder channel is defined by two straight line segments which are spaced from each other at a second dis tance which is larger than the first distance.
