An osmotic device (10) for delivering a beneficial drug, such as an anti-fungal, into the mouth of a human patient is disclosed. The device (10) has a size and shape adapting it to be comfortably retained in the mouth for extended periods of time. The device (10) comprises a wall (12) surrounding a compartment (13) housing a layer of an agent (14) that is insoluble to very soluble in aqueous biological fluids, e.g., saliva, and a layer (16) of a fluid swellable, hydrophilic polymer. A passageway (17) in the wall (12) connects the agent (14) with the exterior of the device (10). The wall (12) is permeable to the passage of aqueous biological fluid but substantially impermeable to the passage of the hydrophilic polymer (16). In one embodiment the beneficial agent (14) has a different color than the hydrophilic polymer (16). The wall (12) is sufficiently translucent to permit the patient to see the amount of drug/beneficial agent (14) remaining to be delivered. Marking lines (19) may be provided on the wall (12) indicating the amount of drug/agent (14) which has been delivered and/or the amount remaining to be delivered.