A medicament delivery device (1) comprises an actuation mechanism by successive operation of which a predetermined number of unit doses of medicament can be dispensed. The device includes a locking mechanism for preventing further operation of the actuation mechanism after dispensing of said predetermined number of unit doses. The locking mechanism comprises a resilient member (51), a formation (18) with which the resilient member (51) is engageable to disable operation of the actuation mechanism, and a barrier member (20) that prevents engagement of the resilient member (51) and the formation (18) until said predetermined number of unit doses has been dispensed. The device (1) may be a dry powder inhaler.
