An insertion guide for a balloon catheter. The insertion guide includes an outer guide tube that defines a passage having an inside diameter sufficient to receive the balloon catheter therethrough. Telescopically receivable within the guide tube is an introducer which defines a lumen centrally thereof. A guide wire is telescoped within the lumen. The guide tube is introduced into a blood vessel by sequentially advancing the guide wire, the introducer and the tube until the distal extremity of the tube is positioned adjacent a stenosis after which the introducer and guide wire are removed. The guide tube has a corrugated wall portion which retains the passage therein in an open condition even when the guide tube assumes an arcuate configuration in traversing an intersection between two blood vessels. Accordingly, the balloon catheter can be introduced, and substantial axial force applied to the proximal extremity thereof is transmitted to the distal extremity to facilitate introduction of the balloon catheter into a stenosis.