A 67-year-old woman presented with palpitations. An ECG showed a narrow-QRS tachycardia at a rate of 160 beats per minute, with visible P waves preceding each QRS complex. The P waves were negative in leads II, III, aVF and V3-V6, with a PR interval of 140 msec. Based on these characteristics, the patient was diagnosed with atrial tachycardia originating from the atria.