A 46 year-old man presented to our clinic with a complaint of palpitation. Electrocardiogram during one of these palpitation episodes showed narrow complex tachycardia with a rate of 190/min. He reported that his palpitation continued despite various antiarrhythmic (metoprolol and propafenon) treatments. His past medical history was unremarkable. Baseline electrocardiogram was in normal limits without any preexcitation. All laboratory values and a baseline transthoracic echocardiography (TTE) were normal. Treatment options were discussed, and electrophysiological study/catheter ablation was scheduled. At electrophysiological study, orthodromic atrioventricular reentrant tachycardia using left lateral concealed accessory pathway was induced. Intravenous heparin (100U/kg) was administered after femoral arterial sheath insertion. Radiofrequency (RF) ablation was performed via retrograde aortic approach without any difficulties (Fig. 1). Ablation was carried out with Medtronic Atakr RF generator and single curve, tip-deflecting bipolar, non-irrigated catheter (Medtronic RF Marinr) with temperature limited to 55℃ and power limited to 40 Watt. After ablation, there was no AP conduction and tachycardia was not induced by programmed stimulation with or without isoproterenol infusion. The morning after the ablation, patient was feeling well and he was discharged with acetylsalicylic acid 100 mg. Two days following ablation, patient was admitted with chest pain lasting for 12 h. Electrocardiogram was unremarkable. TTE revealed a well-circumscribed hypoechogenic mass in the lateral wall of the left atrium, suggestive of an intramural hematoma (Fig. 2). There was no evidence of left ventricular inflow obstruction. He was hemodynamically stable. Then, the patient underwent contrast-enhanced cardiac computed tomography (CT) to investigate the nature of the mass which revealed homogeneous intramural mass consistent with 30- × 19- mm hematoma located in the left lateral wall (Fig. 3, 4). So imaging revealed left atrial intramural hematoma (LAIH). There was no pulmonary vein obstruction. Since there was no hemodynamic instability, watchful monitoring was decided. Acetylsalicylic acid was continued, and analgesics were administered if needed. Follow-up CT 3 days after the index scan revealed partial regression of hematoma. The patient remained well clinically and was discharged from the hospital at the sixth day of hospitalization without any symptoms. A control TTE 2 months later showed complete resolution of intramural hematoma (Fig. 5).