A fixed volume liquid transfer device defined by a small bore tube having an open end for collection of liquids and a plunger in the tube is disclosed. A piston is mounted around the open end and an air plug is mounted in the piston adjacent the open end. Liquid in a test tube is transferred to a testing site by inserting the transfer device into the test tube. As the piston contacts the liquid, the liquid is pumped into the tube. As the transfer device is inserted further, the air plug is actuated to balance air pressure across the piston. The device may then be withdrawn from the test tube and transported to a test site. At the test site, the plunger is depressed to expel the liquid into a testing device.