Biatrial macro-reentrant tachycardia (Bi-MAT) is a relatively uncommon arrhythmia. Sometimes, it can be produced by the left atrial (LA) anterior or septal-anterior linear ablation. However, data concerning the proarrhythmic role of this ablation lesions are lacking. Here, we reported a case of a single-loop Bi-MAT developing after the LA anterior ablation line performed in one patient with persistent atrial fibrillation.