An oscillating positive respiratory pressure apparatus and a method of performing oscillating positive respiratory pressure therapy. The apparatus includes a housing having an interior chamber, a chamber inlet, a chamber outlet, an exhalation flow path defined between the inlet and the outlet, and a restrictor member rotatably mounted within the interior chamber. The restrictor member has an axis of rotation that is substantially perpendicular to the flow path at the inlet, and includes at least one blocking segment. Rotation of the restrictor member moves the at least one blocking segment between an open position and a closed position. Respiratory pressure at the chamber inlet oscillates between a minimum when the at least one blocking segment is in the open position and a maximum when the at least one blocking segment is in the closed position. By exhaling into the apparatus, oscillating positive expiratory pressure therapy is administered.