Objective: Renin-angiotensin system may be activated during atrial fibrillation (AF). Our aim was to evaluate plasma renin activity (PRA) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in patients with different AF types who had normal left ventricular (LV) systolic function. Methods: This cross-sectional study included 97 patients with recent (≤7 days), persistent (7 days to 12 months) and permanent AF (>12 months), and age- and sex-matched 30 controls with sinus rhythm. Plasma levels of PRA and NT-pro-BNP were measured and presented as median (25th-75th percentiles). Echocardiographic examination was performed in all population. Variance and logistic regression analyses were also used for multiple comparisons and independent predictors, respectively. Results: Median NT-proBNP levels were higher in overall patients with AF than in controls [114 (63-165) vs 50 (38-58) pg/ml, p<0.001), but PRA level was comparable in both groups. Similarly, NT-proBNP levels were also higher in all subtypes of AF compared with controls (p<0.05). In addition, there was a significant difference in NT-proBNP level among recent, persistent and permanent AF subtypes (p=0.001). This difference mainly derived from the recent AF subtypes. Whereas PRA level was similar in all AF subtypes and controls. Age was an independent predictor of PRA level ≥1.9 ng/ml/hour (OR=1.1, 95% CI 1.01-1.23, p=0.03). With NT-proBNP level ≥52 pg/ml, independent predictors were age (OR=1.1, 95% CI 1.01-1.19, p=0.02), presence of persistent and/or permanent AF (OR=6.8, 95% CI 1.03-45.7, p=0.04) and left atrial dimension (OR=1.2, 95% CI 1.03-1.36, p=0.02). Conclusion: Plasma NT-proBNP levels can be associated with AF and its subtypes in patients with normal LV systolic function, whereas there was no association between PRA levels and AF.