Acute rheumatic fever (ARF) remains a serious problem for public health, and it is common in developing countries. It has a wide range of presentation and in some settings it can appear a dramatic event. Various rhythm problems such as first, second and third-degree atrioventricular blocks, premature contractions, accelerated junctional rhythm, ventricular tachycardia, and Torsades de pointes may occur during the acute stage of the disease. We report a case of narrow QRS tachycardia in whom a palpitation was the only symptom of rheumatic carditis. The tachycardia returns to normal after the disease becomes inactive with acetylsalicylic acid treatment.