Abstract: Objective: To analyze six unusual difficult cases in 130 patients of radiofrequency catheter ablation(RFCA) for supraventricular tachycardia, and to assess safe approaches and effective procedures. Methods: Three cases had right-sided accessory pathways(AP). One of them was manifest. It was induced atrial fibrillation with mechanical stimulation of catheter in the operation. RFCA success was achieved with unipolar mapping. The other two were obscure so we usedes 11 sinus-ventricular-sinus" mapping and discharged in the sinus rhythm to discontinue AP. Two cases had left-sided AP. One of them was atrioventricular reentrant tachycardia (AVRT) with long sinus pause and fainted repeatedly. Alter RFCA, the following symptoms disappeared. The other was left in posterioseptum AP because his △HA was 32ms. The last case was solwfast atrioventricular node reentrant tachycardia (AVNRT) complicated with deformity chest and cardiovascular, so we operated the catheter difficultly. ResultS: All the ablation procrdures were successful. Conclusions: The key to RFCA in unusual type cases is to take special tactics according to each patient's Fharacteristic of eletrophysiology and anatomic structure.