Undilatable coronary lesions, due to coronary calcification, are encountered with increasing frequency. Percutaneous intervention of such lesions comes with the risk of stent underexpansion, which increases the risk of stent thrombosis and restenosis. A variety of techniques and devices are available to assist the interventionist in the treatment of calcified lesions. The OPN NC (SIS-Medical AG, Winterthur, Switzerland) is a high-pressure balloon (rated burst pressure 35 atm) that uses a novel, twin-layer balloon technology to ensure uniform balloon expansion, eliminating "dog-boning." We report four cases of successful treatment of calcified lesions with the OPN NC balloon after dilatation with standard noncompliant balloons to high-pressure failed.