Although radiofrequency (RF) catheter ablation has been shown to be an effective treatment strategy in patients with supraventricular tachycardia, RF ablation may lead to potentially serious complications. We describe a case of a 65-year old man who was transferred for catheter ablation of typical atrial flutter. 21 RF applications (mean energy: 81+/-9 watts) were applied in the temperature-controlled mode (70 degrees C) between a 8-mm tip electrode and an indifferent electrode using a high-power RF generator (100 watts) until bi-directional atrial isthmus block was achieved. After the procedure, a third-degree skin burn (10x2 cm) was observed at the lateral edge of the adhesive indifferent electrode whereas the medial edge of the electrode was not fully attached to the skin surface. This case is one out of 1128 ablation procedures (0.09 %) at our institution using a high-power RF generator. The present study demonstrates a severe skin burn induced by mal-attachment of an indifferent electrode during RF ablation. Long RF energy application times, high-power settings, and heavy sedation may have contributed to the observed severity of skin damage.