A 31-year-old woman with idiopathic premature ventricular contractions originating from the tricuspid annulus (TA) underwent electrophysiological testing. Activation mapping with a 20-pole bipolar Halo-type catheter positioned along the TA revealed the earliest ventricular activation at a site between 7 and 8 o'clock along the TA. A reversal in the polarity of the local ventricular electrograms was observed between the two neighbouring electrode pairs of the TA catheter. Successful catheter ablation was achieved at the ventricular site between those electrode pairs. A Halo-type catheter may be effective for mapping and catheter ablation of ventricular arrhythmias originating from the TA. © The Author 2008.