Rotational coronary atherectomy is an effective treatment for calcified ostial lesions. We report a case of guidewire transection during rotational atherectomy of a right coronary artery ostial stenosis. Guide catheter dislodgement appeared to have caused prolapse and kinking of the guidewire. Advancement of the burr over the kinked wire resulted in transection. The wire fragment was retrieved successfully using an inflated fixed-wire balloon catheter. This report illustrates the importance of excellent coaxial guide catheter alignment with rotational atherectomy and suggests that operators be vigilant to possible damage to the radiolucent rotational atherectomy guidewire.