There are only limited data on the prevalence and risk factors for postoperative atrial fibrillation (AF) after elective abdominal surgery. We retrospectively studied the clinical characteristics and hospital outcomes in 563 consecutive patients (mean age: 67 +/- 13 years, 245 men) with colorectal cancer who underwent elective colectomy. The baseline clinical characteristics of patients who underwent open (OC) versus laparoscopic colectomy (LC) were similar. Postoperative AF developed in 25 patients (4.4%). Patients who developed postoperative AF were older (P = 0.017), had a higher prevalence of hypertension (P = 0.05), more major postoperative events (P = 0.02), an elevated neutrophil count on postoperative day (POD) 1 (P = 0.007), longer hospitalizations (P = 0.02), and were more likely to undergo OC (P = 0.067). In multiple regression analysis, independent predictors of postoperative AF were OC (odd ratio: 3.3, 95% confidence interval: 1.3-8.0, P = 0.008), and an elevated neutrophil count on POD 1 (odd ratio: 3.2, 95% confidence interval: 1.3-7.8, P = 0.01). The incidence of postoperative AF after elective colorectal cancer surgery was approximately 4%. Postoperative AF was more commonly observed in patients with OC versus LC and in those with elevated postoperative neutrophil counts.