An improved needle-free intravenous injection port assembly is disclosed. Embodiments include a boot valve with a helical surface, a boot valve and septum which mate with mechanical interference, a spike with a rough outer surface coated with a lubricant, a septum having a shoulder and a single continuous swabbable surface, a septum and a boot valve which are pre-punctured, a septum with a frustroconical extension and a combination single piece septum and boot valve. The injection port assembly provides zero fluid displacement during coupling and uncoupling.