a balloon for a dilatation catheter is formed to define relatively thin cone and neck segments at the opposite ends of the balloon by forming the balloon in a plurality of separate very thin layers . the balloon is built up from a plurality of layers including an inner layer which defines a complete balloon having a cylindrical midportion , cones at its ends and necks at the ends of the cones . each successive outer layer is trimmed to be shorter than the next adjacent innermost layer , the trimming being effected in the region of the cones . the composite balloon thus formed has a staggered wall thickness in the region of the cones as to define a cone that is approximately uniform in wall thickness in a direction extending toward the neck region . the resulting balloon will be better adapted to collapse to a low profile about the catheter shaft on which it is mounted .