This invention provides catheter assemblies and methods for insertion of a catheter into a vessel. The assemblies include a resilient valve in the hub of the catheter that can be opened by pressure from a male luer fitting. The methods include piercing a vessel with the needle and catheter of the assembly, retraction of the needle component thus closing the resilient valve. Finally the catheter can be accessed by applying a male luer fitting to the catheter hub and a shoulder of the resilient valve.
