Marfan's syndrome is a common connective tissue disease with different musculoskeletal, ophthalmic and cardiac manifestations. Marfan's patients carry increased risk for cardiac arrhythmias. Only three cases of atrial flutter in Marfan's patients are described in the literature. We report a fourth case of a young Marfan's patient who presents with typical atrial flutter after motor vehicle accident. After electrical cardioversion, sinus rhythm was restored but he had recurrent atrial flutter on follow up. The patient then underwent electrophysiological study and successful radiofrequency catheter ablation of the flutter circuit. Since discharge, the patient has had no documented arrhythmias on follow up.