Coronary involvement of polyarteritis nodosa (PAN) is rarely identified at premortem. Herein, we report a case of PAN presenting as acute myocardial infarction (MI). A 66-year-old man without previous history of heart disease presented with excruciating substernal chest pain of 3 hours duration. On admission, cardiac enzyme and ECG changes were compatible with acute MI of inferior wall. Emergency coronary angiography showed multiple aneurysmal dilatations of both left and right coronary arteries (RCA) and total occlusion with large thrombi at mid-RCA. After balloon angioplasty and intracoronary urokinase, huge coronary aneurysm was defined at mid-RCA and coronary flow partially improved. The patient was transferred to coronary care unit and continous intravenous heparin infusion was started. On the 7th hospitalization day, the patient was discharged in good condition. Two months later, follow-up coronary angiography showed no significant luminal narrowings in RCA with multiple aneurysmal dilatation, but abdominal angiography revealed multiple aneurysms in right renal and superior mesenteric arteries. These findings were compatible with the diagnosis of PAN. The patient was started on prednisone 60mg once daily and cytoxan 125mg bid. At follow-up 8 month later, there was no recurrence of symptoms.