The goal of the present study was to determine the safety and efficacy of a modified off-pump biatrial mini-maze procedure to treat long-standing persistent atrial fibrillation (AF). Patients with long-standing persistent AF underwent our modified mini-maze procedure using bipolar radiofrequency ablation. Those patients first underwent a mini-maze procedure using the Dallas lesion set protocol. Second, a purse-string suture was performed on the right atrium, and then 4 ablation lesions were made to the superior vena cava, the inferior vena cava, the appendix of the right atrium and the tricuspid valve annulus from the purse-string suture point by the bipolar radiofrequency clamp. After the operation, the patients were followed up at 3, 6 and 12 months and every year thereafter. A total of 102 patients were included in the study. There were no deaths, no surgical re-exploration for bleeding and no permanent pacemaker implants. The intraoperative cardioversion rate was 42.2% (43/102). A follow-up at intervals of 3, 6, 12, 24, 36 and 48 months showed that a success rate free from long-standing persistent AF was 95.1% (97/102), 94.4% (85/90), 94.8% (73/77), 91.5% (54/59), 90.3% (28/31) and 86.4% (19/22), whereas freedom from AF in patients off antiarrhythmic drugs was 88.2% (90/102), 85.6% (77/90), 81.8% (63/77), 78.0% (46/59), 74.2% (23/31) and 68.2% (15/22), respectively. The modified biatrial mini-maze procedure proved to be safe and feasible. Early follow-up demonstrated an acceptable success rate free from AF.