SUMMARY -Postoperative atrial fi brillation is a common complication after lung resection. It is burdened by increased mortality and morbidity, prolonged hospitalization, and higher resource utilization in thoracic surgery patients. Th erefore, some kind of pharmacological prophylaxis is recommended. In our patients, diltiazem, a calcium antagonist, is administered. We collected data on all 608 patients having undergone lung resection (no less than lobectomy) between November 2012 and May 2015. Th is period included patients having received diltiazem during their postoperative stay in our Intensive Care Unit and surgical ward, and those that did not receive it. Patients having had atrial fi brillation before the surgery and patients with cardiac pacemaker were excluded from the trial. Other patients were divided into three groups: patients with some kind of antiarrhythmic therapy before and continued after the surgery; patients with diltiazem prophylaxis; and patients without any antiarrhythmic prophylaxis. Th e data collected were statistically analyzed. We found no statistically signifi cant diff erence in the incidence of postoperative atrial fi brillation among the groups (p<0.05).