Objective: High neutrophil/lymphocyte ratio (NLR) has been associated with post-operative AF development in patients who underwent cardiac surgery. In this study, effectiveness of NLR for prediction of recurrence after electrical cardioversion (CV) in non-valvular AF was investigated. Methods: A total of 149 patients who underwent a successful CV were included in this prospective cohort study. Baseline complete blood cell count, routine biochemical tests, high sensitive C-reactive protein (hs-CRP), and echocardiographic measurements were examined. After CV, patients were monitored over six months for recurrence. Baseline characteristics of recurrence group were compared with sinus rhythm group by using Student's t -test. Logistic regression analysis was used to determine predictors of recurrence. Results: Recurrence occurred in a total of 46 patients (30.9%). Median AF duration [16 (IQR:14.25) vs. 12 (IQR:11) months, p=0.01], baseline hs- CRP [9.80 (IQR: 8.50) mg/dL vs. 4.28 (IQR: 5.65) mg/dL, p=0.002] and left atrium (LA) diameter (4.5±0.4 cm, 4.3±0.5 cm, p=0.023) were significantly higher in the recurrence group than sinus rhythm group. Median NLR was comparable in recurrence and sinus groups [2.38 (IQR: 2.09) vs. 2.23, (IQR: 1.23) p=0.96, respectively]. There was a weak correlation between NLR and hs-CRP (r=0.22, p=0.05) and age (r=0.24, p=0.02). In multiple logistic regression analysis, hs-CRP [OR: 1.34 (1.09-1.65 95% CI) p=0.006], LA diameter [OR: 11.92 (1.84-77.07 95% CI) p=0.01], spontaneous echo contrast positivity, [OR: 5.40 (1.04-12.02 95% CI) p=0.045] and systolic blood pressure [OR: 1.05 (1.01-1.10 95% CI) p=0.03] were independent predictors of AF recurrence. Conclusion: NLR failed to predict AF recurrence after a successful electrical CV, but hs-CRP remained an inflammatory marker of AF recurrence. © Telif Hakki̇ 2013 AVES Yayi̇ncili̇k Ltd.