<p>A breath actuated dry powder inhaler (1), comprising a substantially disc shaped air circulation chamber (2) for de-agglomeration of entrained powdered medicament using the energy of the inspiratory air stream. The chamber (2) has a substantially circular or polygonal sidewall (3) extending about a central axis (4) between top (5) and bottom (6) walls of the chamber (2) so that the height (h) of the chamber (2) is smaller than its diameter (d). A plurality of air supply channels (7) disposed about the circumference of the chamber (2), which channels (7) extend from joint (27) or separate (28) air inlets and which channels (7) enter the chamber (2) substantially tangentially to its sidewall (3). At least one of the supply channels (7) extends through a powder dose supply region (8) of the inhaler (1). The chamber (2) further comprises an air outlet (9) axially extending from a discharge opening (10) in the centre of the top (5) or bottom (6) wall of the chamber (2) and connects to a discharge channel (12) that extends to a mouthpiece (13). The discharge channel (12) connects substantially transversely to the air outlet (9) of the chamber (2). <IMAGE></p>