A 28-year-old-man admitted to emergency department with ventricular tachycardia. Patient had drunk 3 cans of 250-mL energy drink 5 hours before the basketball match; he had palpitation and nausea before the match. After 30 minutes of the match, during the break, patient lost his consciousness. On admission, normal cardiac rhythm was achieved by cardioversion, and the patient was hospitalized and died on the third day. Energy drinks generally contain caffeine, taurine, various vitamins, glucose, and herbal extracts such as guarana and ginseng. Especially in high doses, caffeine can cause palpitations and supraventricular and ventricular arrhythmia. Energy drink consumers should be informed about their severe adverse effects in case of overuse.