A manually operated metered dose inhaler having a main body arranged to retain a medicament canister of predetermined configuration for movement of the canister relative thereto and a dose counter; the dose counter comprising: an incremental counting system for counting doses, the incremental counting system having a main body, an actuator arranged to be driven in response to canister motion and to drive an incremental output member in response to canister motion, the actuator and incremental output member being arranged to provide a start configuration at which the actuator is spaced from a ratchet output member, a reset configuration at which the actuator is brought into engagement with the incremental output member during a canister fire sequence, and an end configuration at which the actuator disengages from a ratchet output during a canister fire sequence and the actuator and incremental output member being further configured to have predetermined canister fire and count configurations in a canister fire sequence, the canister fire configuration being determined by a position of the actuator relative to a datum at which the canister fires medicament and the count configuration being determined by a position of the actuator relative to the datum at which the incremental count system makes an incremental count, wherein the actuator is arranged to reach a position thereof in the count configuration at or after a position thereof in the canister fire configuration wherein the incremental output member comprises a ratchet wheel having a plurality of circumferentially spaced teeth to engage the actuator and wherein the dose counter further comprises a count pawl with a tooth arranged to engage the incremental output member, the tooth and incremental output member being arranged to permit one way incremental relative motion therebetween, and in which the count pawl is fixedly mounted on the main body of the incremental count system and in which the count pawl is arranged to be capable of repeatedly engaging equi-spaced teeth of the incremental output member in anti-back drive interlock configurations as the dose counter is operated, the count pawl being positioned so that the incremental output member is halfway moved from one anti-back interlock configuration to the next when the actuator and incremental output member are in the end configuration thereof. an incremental counting system for counting doses, the incremental counting system having a main body, an actuator arranged to be driven in response to canister motion and to drive an incremental output member in response to canister motion, the actuator and incremental output member being arranged to provide a start configuration at which the actuator is spaced from a ratchet output member, a reset configuration at which the actuator is brought into engagement with the incremental output member during a canister fire sequence, and an end configuration at which the actuator disengages from a ratchet output during a canister fire sequence and the actuator and incremental output member being further configured to have predetermined canister fire and count configurations in a canister fire sequence, the canister fire configuration being determined by a position of the actuator relative to a datum at which the canister fires medicament and the count configuration being determined by a position of the actuator relative to the datum at which the incremental count system makes an incremental count, wherein the actuator is arranged to reach a position thereof in the count configuration at or after a position thereof in the canister fire configuration wherein the incremental output member comprises a ratchet wheel having a plurality of circumferentially spaced teeth to engage the actuator and wherein the dose counter further comprises a count pawl with a tooth arranged to engage the incremental output member, the tooth and incremental output member being arranged to permit one way incremental relative motion therebetween, and in which the count pawl is fixedly mounted on the main body of the incremental count system and in which the count pawl is arranged to be capable of repeatedly engaging equi-spaced teeth of the incremental output member in anti-back drive interlock configurations as the dose counter is operated, the count pawl being positioned so that the incremental output member is halfway moved from one anti-back interlock configuration to the next when the actuator and incremental output member are in the end configuration thereof.