Focal-source atrial tachycardias (ATs) are common following atrial fibrillation ablation. They can be hard to map, but with due patience and perseverance, the source of earliest activation can usually be located. It is very useful to first rule out a macro reentrant tachycardia, and following this, start homing in on the source. Mapping with a multi-electrode may help pinpoint the earliest site and can often allow demonstration of activity spanning most of the tachycardia cycle length. Once entrainment has confirmed the source of the AT, the target can be ablated.