This study was designed to test whether nonsteroidal anti-inflammatory medications could reduce the frequency of atrial fibrillation after coronary artery bypass graft surgery. The study was designed as an open-label, randomized trial. Patients undergoing first-time coronary artery bypass graft surgery were considered eligible. Patients with a history of atrial fibrillation, serum creatinine >2.0 mg/dL, on antiarrhythmic treatment, and those undergoing concomitant valvular surgery were excluded. The study was conducted in a single, university-affiliated community hospital. The researchers' role in the study was restricted to randomizing the patients and collecting data. The primary clinical care team made all decisions regarding patient care. One hundred patients were randomized to two groups: one received 30 mg ketorolac intravenously every 6 hours until able to take oral medications, at which point the patients were switched to 600 mg ibuprofen orally three times a day; the other group received conventional treatment. The primary end point of the study was incidence of atrial fibrillation in the immediate postoperative period. Atrial fibrillation occurred in 14 patients (28.6%) in the conventional treatment group vs. five patients (9.8%) in the ibuprofen group (p<0.017). Nonsteroidal anti-inflammatory medications were relatively safe and effective in significantly reducing the incidence of atrial fibrillation after coronary artery bypass graft surgery.