A dilator (10) for sheathless access to a vessel of a patient, having a distal portion (14) with a maximal outer diameter that extends from a distal end (12) to a guidewire exit port (16) and a proximal portion (18) with a reduced profile that extends from the guidewire exit port to the proximal end (20) and a lumen (22) that extends between the distal end and the guidewire exit port. A first guidewire (42) may be positioned within the vessel and the dilator advanced over the guidewire. A guide catheter may then be advanced over the dilator.