Wolff-Parkinson-White (WPW) syndrome is defined as the presence of an accessory atrioventricular pathway which is manifested as delta waves and short PR interval on electrocardiography (ECG).  However, some WPW cases do not have typical findings on ECG and may remain undiagnosed unless palpitations occur.  Sudden cardiac death may be the first manifestation of WPW and develops mostly secondary to degeneration of atrial fibrillation into ventricular fibrillation.  In this report, we present a case of undiagnosed WPW with minimal preexcitation on ECG and who suffered an episode of malignant arrhythmia as the first manifestation of the disease.