Abstract: A compliance monitor (20) is attachable to or forms part of a drug delivery device, such as an inhaler (2). The monitor comprises a flexible portion (38) to enable a switch which is actuated by a user when delivering a dose of medicament. The monitor further comprises a sensor for sensing whether the device is properly positioned in contact with or relative to the user's body for administration of the medicament. For example, where the device is an inhaler and the sensor a temperature sensor, temperature variations caused by insertion of an inhaler mouthpiece into the user's mouth indicate whether the dose has been delivered into the patient's mouth. A memory in the compliance monitor stores a compliance record indicating whether or not the device was properly positioned each time a dose was delivered.