Experimental studies of hub contamination of intravenous catheters were done comparing the standard connection method (Luer-Lock connector) with a newly invented connection method (I system). Immersion of the connection sites into a bacteria-containing solution showed no bacterial contamination of the medium in any tubing. The second experiment investigated whether bacterial contamination would occur during a tubing change procedure. A high incidence of bacterial contamination was seen with the Luer-Lock connector, but no bacterial contamination occurred with the I system. These experiments suggest that the use of Luer-Lock connectors is associated with a high risk of bacterial contamination during tubing change, but the I system can prevent contamination during tubing change, which cannot be avoided with Luer-Lock connector.