A medicament delivery device (1) comprises a metering member (25) mounted for rotation adjacent a reservoir (22) containing a bulk quantity of medicament. The metering member (25) is adapted when at a filling position to volumetrically meter a desired dose of medicament from the reservoir (22). By rotation of the metering member (25) in a first sense said dose is transferred to a dispensing position at which the dose can be dispensed from the device (1). The metering member (25) and/or a component (90) to which the metering member (25) is operably linked is provided with formations (95) effective to prevent reverse rotation of the metering member (25) from the filling position.