An introducer assembly (40) for use in the deployment of implantable medical devices such as stents and stent grafts includes a carrier element (20), a dilator tip (18) located at the distal end of the carrier element (40) and sheath (32) movable between a device covering position and a device deployment position. In the device deployment position, a restricted annular gap (34) is created between the distal end (36) of the sheath (32) and the proximal end (38) of the dilator tip (18). The gap (34) is restricted by a restriction mechanism (50) located at the proximal, external end, of the introducer assembly (40). The gap (34) allows for the progressive deployment of the medical device from the introducer (40) and for simultaneous retraction of the dilator tip (18) thereby avoiding snagging of the dilator tip (18) against the wall of a patient's vessels and of the medical device.