Abstract: A de-agglomerator is provided for use with a breath-actuated dry powder inhaler for breaking up aggregates and micronizing particles of dry powder prior to inhalation of the powder by a patient using the inhaler. The de-agglomerator includes an inner wall defining a swirl chamber extending along an axis from a first end to a second end, a dry powder supply port, an inlet port, and an outlet port. The supply port is in the first end of the swirl chamber for providing fluid communication between a dry powder delivery passageway of an inhaler and the first end of the swirl chamber. The inlet port is in the inner wall of the swirl chamber adjacent to the first end of the swirl chamber and provides fluid communication between a region exterior to the de-agglomerator and the swirl chamber.