Objective. To evaluate the association of BNP and CRP with the development of postoperative atrial fibrillation following coronary artery bypass grafting surgery. Methods. The series consists of 125 patients (aged 65 ± 9 years), who underwent isolated CABG-surgery. BNP and CRP levels were measured pre- and 24 hours postoperatively and their correlation to the development of postoperative AF was analyzed. Results. Forty-four patients (35%) developed AF postoperatively. They were significantly older (68 ± 8 versus 63 ± 9, P = 0.01) and predominantly nonsmokers (18% versus 46%, P = 0.004), compared to the non-AF cases. In addition they showed significant higher preoperative mean BNP levels of 629 versus 373 pg/mL (P = 0.019). Postoperative BNP levels were significantly higher in both groups (AF-group: 1032 pg/mL versus non-AF group: 705 pg/mL; P<0.001), while there was a trend of more increased postoperative levels in AF-cases (P = 0.065). AF-episodes appeared significantly more frequent in the two highest quartiles of BNP levels with 44% (P = 0.035). On the contrary pre- and postoperative CRP levels were not associated with AF. Multivariable analysis revealed only increased preoperative BNP levels as independent predictor for postoperative AF (P = 0.036). Conclusion. Elevated preoperative BNP serum levels are associated with the development of post-CABG AF, while CRP does not seem to be influential.