Morbid obesity presents many clinical problems. Especially, morbid obesity has a significant effect on airway management and pulmonary function. We experienced a cardiac arrest of a morbidly obese (Body Mass Index of about 62 kg/m²). 21-year-old male patient that necessitated cardiopulmonary resuscitation (CPR). The patient was scheduled for an emergency cystoscopy under local anesthesia. After change to supine position in the operation room, dyspnea, tachypnea, agitation, and, subsequently, cardiac arrest developed.