An improved catheterization device of the type in which a flexible catheter overlays a rigid or semi-rigid stylet, the improvement residing in the preformed arcuate curvature of the stylet, the curvature of which can be in the form of a circular arc, an elliptical arc, or an irregular curvature, for facilitating insertion of the catheter into the blood vessel of a subject with reduced risk of vascular damage or where the direct path to the blood vessel is obstructed, and methods for its use.