Background Detailed information about the topographic distribution of focal left atrial tachycardias (FLATs) is limited. Methods and Results A total of 143 atrial tachycardia (AT) foci were successfully ablated in 140 patients (56 men, mean age 44.6{|±17.9 years). In 36.4% (52/143 ATs), a left atrial (LA) origin of the tachycardia was identified from the site of successful ablation. In 46% (24/52) of FLATs, the site of origin (SO) was near the ostium of a pulmonary vein (PV), and in 36.5% (19/52), the SO was near the mitral annulus (MA). In the remaining ATs, the SO was in the left atrial appendage (LAA), septum, LA roof and inside the coronary sinus. P waves in V₁ showed biphasic morphology with an initial negative component in most FLATs originating from the septal MA, superior MA, and LAA. However, P waves in V₁ were positive in all patients with FLATs originating from PVs. Negative P waves in aV_L were always observed in FLATs originating from left PVs. The mean cycle length of FLATs from PVs was significantly shorter than that from the MA. Conclusion Knowledge of the topographic distribution, P-wave morphology, and tachycardia cycle length facilitates successful ablation of FLATs. (Circ J 2005; 69: 205 - 210)