A previously healthy 35-year-old woman experienced chest discomfort following mild blunt chest trauma while waterskiing. During the following 48 h, she underwent evaluation in two separate emergency departments (EDs) where she was found to have normal ECGs and cardiac enzyme values. She was subsequently discharged from both EDs. Twelve hours after the second ED visit, she was discovered unconscious at home and was resuscitated from ventricular fibrillation. Emergency cardiac catheterization demonstrated moderate circumflex disease without angiographic evidence of a false lumen or intimal flap. Left ventriculography demonstrated posterolateral wall hypokinesis. Eight days after remaining ventilator-dependent and unconscious, the patient was declared brain-dead. At autopsy, the patient was found to have a dissection of the circumflex artery. Waterskiing is an unusual source of cardiac trauma; however, we believe this to be the first reported case of dissection in the circumflex artery following blunt chest trauma.