An inhaler for delivering dry-powder medicament to a patient from an open blister pocket of a blister pack, the blister pack being in the form of a flexible elongate strip having a length direction, a width direction and a thickness direction, the blister pack comprising a base sheet having a plurality of recesses formed in the thickness direction of the blister pack and spaced along the length direction of the blister pack,and the blister pack further comprising a cover sheet peelably sealed to the base sheet to define a plurality of blister pockets each containing a measured dose of the medicament, the inhaler comprising: a medicament dispensing mechanism for opening the blister pockets of the blister pack, the medicament dispensing mechanism comprising means for peeling the cover sheet away from the base sheet of the blister pack; a housing for enclosing used and unused portions of the blister pack together with the medicament dispensing mechanism; and a manifold through which air can be drawn in use of the inhaler, the manifold comprising an air inlet for receiving external air, at least one medicament aperture (127a, 127b) for communicating with an opened pocket of the blister pack to enable entrainment of the medicament by the air drawn through the manifold, and an air outlet for delivery of the entrained medicament to the patient, wherein the medicament dispensing mechanism comprises a driven cover sheet winding wheel for winding up the used portion of the cover sheet, and wherein the inhaler is characterized in that the housing defines internal transverse walls extending in the width direction of the blister pack for isolating the used portion of the cover sheet from the unused portion of the blister pack, wherein the housing comprises an inner housing member arranged within at least one outer housing member (103, 105), and wherein the internal transverse walls are defined by the inner housing member, wherein the internal transverse walls extend in a perpendicular direction from a base surface of the inner housing member, the base surface of the inner housing member being arranged to support a side edge of the unused portion of the blister pack, and wherein the at least one outer housing member (103, 105) is arranged to support an opposite side edge of the unused portion of the blister pack such that surfaces of the inner housing member and the at least one outer housing member (103, 105) are arranged to substantially enclose the unused portion of the blister pack, and wherein the internal transverse walls of the housing define separate compartments for accommodating the used portion of the cover sheet and the used portion of the base sheet, the separate compartments being arranged to prevent loose medicament in the compartments from contaminating the unused portion of the blister pack. a medicament dispensing mechanism for opening the blister pockets of the blister pack, the medicament dispensing mechanism comprising means for peeling the cover sheet away from the base sheet of the blister pack; a housing for enclosing used and unused portions of the blister pack together with the medicament dispensing mechanism; and a manifold through which air can be drawn in use of the inhaler, the manifold comprising an air inlet for receiving external air, at least one medicament aperture (127a, 127b) for communicating with an opened pocket of the blister pack to enable entrainment of the medicament by the air drawn through the manifold, and an air outlet for delivery of the entrained medicament to the patient, wherein the medicament dispensing mechanism comprises a driven cover sheet winding wheel for winding up the used portion of the cover sheet, and wherein the inhaler is characterized in that the housing defines internal transverse walls extending in the width direction of the blister pack for isolating the used portion of the cover sheet from the unused portion of the blister pack, wherein the housing comprises an inner housing member arranged within at least one outer housing member (103, 105), and wherein the internal transverse walls are defined by the inner housing member, wherein the internal transverse walls extend in a perpendicular direction from a base surface of the inner housing member, the base surface of the inner housing member being arranged to support a side edge of the unused portion of the blister pack, and wherein the at least one outer housing member (103, 105) is arranged to support an opposite side edge of the unused portion of the blister pack such that surfaces of the inner housing member and the at least one outer housing member (103, 105) are arranged to substantially enclose the unused portion of the blister pack, and wherein the internal transverse walls of the housing define separate compartments for accommodating the used portion of the cover sheet and the used portion of the base sheet, the separate compartments being arranged to prevent loose medicament in the compartments from contaminating the unused portion of the blister pack.