Abstract: A dosage dispenser assembly for containers to dispense liquids in the containers. The assembly includes elongated hollow barrel and an arrangement for removably mounting the barrel over the discharge opening in the container so that the port in the barrel in the seated position is disposed adjacent the bottom of the container. A stop sleeve of generally tubular configuration engages internally of the barrel and has at least two key ways of different axial depth defining cam follower surfaces. A plunger engages in the barrel having a lug element and is rotatable relative to the stop sleeve between a position wherein the plunger tip is fully seated in the barrel and another position wherein the plunger may be activated axially to draw a predetermined dosage of liquid contents into the barrel.