A nasal delivery device for and method of delivering substance to a
nasal cavity of a subject, the delivery device comprising: a nosepiece unit including a nosepiece for fitting to a
nostril of a subject and a
nozzle through which substance is in use delivered, preferably substantially axially to a longitudinal axis of the nosepiece, to the respective
nasal cavity, wherein at least a tip element of the nosepiece has, at least in one configuration, an elongate lateral section which has a longer dimension in a first, sagittal direction than a second direction orthogonal to the sagittal direction, such that, when the nosepiece is inserted in the
nasal cavity of the subject, the longer dimension of the nosepiece acts to engage lower and upper surfaces of the nasal cavity, preferably at the
nasal valve, and expand the same in the
sagittal plane; and a delivery unit for delivering substance through the
nozzle of the nosepiece.