There is a potential hazard during examinations of patients with attached or implanted long conductors, e.g. ECG leads: an MR exam of the lumbar spine of a patient was performed in a 1.5-T scanner under ECG monitoring using equipment marked as MR compatible. Standard cabling of 370-cm length was guided without loops from the electrodes through the caudal opening of the magnet bore. During a sagittal T1-weighted turbo-spin-echo scan suddenly a flame of approximately 3 cm arose from the patient's shirt, close to the position of the electrodes. The supervising anaesthesiologist extinguished the flames with his hands. A subsequent physical examination revealed second- to third-degree burns. The analysis of the incident revealed that high voltages can be induced in straight conductors without loops as ECG cables by coupling with the electric component of the HF field. Local heating or sparking can cause an open flame at the position of the electrodes. This danger exists even with ECG equipment that is specifically marked as MR compatible.