A process for forming a catheter balloon includes subjecting a tubular parison in a mold to molding fluid pressure. The resulting catheter balloon includes a balloon portion having two ends and tubular leg portions extending from either end. The ends of the balloon portion are tapered to the tubular leg portions. While in the mold, the tubular leg portions are drawn axially sufficiently to form permanent creases in the tapered ends. This drawing may be sufficient to cause the material of the tapered ends to exceed the yield strength, particularly with the balloon material in a malleable state. Anomalies on tapered parts of the mold may include ribs or spiral ribs to assist in the creasing process.
