A nasal delivery device for delivering substance to a nasal airway of a subject, comprising: a nosepiece for fitting to a nostril of a subject, the nosepiece including a first delivery outlet through which substance is in use delivered to the nasal airway of the subject, and at least one second delivery outlet through which at least one gas flow, separate to an exhalation breath of the subject, is in use delivered to the nasal airway of the subject a delivery unit for delivering substance through the first delivery outlet of the nosepiece and a gas supply unit for supplying a gas flow through the at least one second delivery outlet of the nosepiece.
