A closed specimen collection system for blood samples includes a collection tube that has a shaped nozzle adapted to fit sealably into a port connected to a centrally inserted venal catheter. A protective cover for the nozzle is attached to the collection tube and has an internal, female thread that mates to a male thread on the port. A specimen container has a hollow body, a front end and a back end. The front end has an aperture sized and shaped to attach to the collection tube. The aperture is sealable after removal of the collection tube. A piston fits closely within the hollow body and is attached to an actuating rod. When the port is connected to the collection tube, the collection tube is connected to the specimen container and the actuating rod is pulled toward the back end, blood will flow into the container in a sterile condition.
