Background: The aim of this study was to evaluate whether risk for postoperative atrial fibrillation in women is related to preexisting inflammation as detected by plasma C-reactive protein (CRP) concentrations. We further sought to assess the importance of atrial fibrillation for outcome after cardiac surgery in women. Methods: The CRP was measured before coronary artery bypass grafting and (or) valvular surgery using cardiopulmonary bypass in 141 women. Univariate and multivariate analyses were used to evaluate for differences in CRP levels between women with and without atrial fibrillation, and to assess for the importance of the arrhythmia and postoperative outcomes. Results: Atrial fibrillation developed in 46 (33%) women. Neither CRP concentrations (median ± standard error, 13.3 ± 2.5 mg/L vs 11.7 ± 1.4 mg/L, p = 0.847), nor the frequency of elevated levels (defined as > upper 95% confidence interval or >19.2 mg/L) (19% vs 21%, p = 0.807) differed between women with or without atrial fibrillation. Patient age and previous stroke, but not CRP levels, were independently associated with atrial fibrillation. Women with atrial fibrillation were more likely to have low cardiac output syndrome (p = 0.018), stroke (p = 0.031), longer duration of hospitalization in the intensive care unit (p = 0.012) and on the postoperative (p = 0.0008) ward, and they were more likely to require an extended care facility after surgery (p = 0.046). Conclusions: In contrast to findings from studies that have included mostly men, preoperative CRP concentrations are not associated with risk for atrial fibrillation after cardiac surgery for women. Postoperative atrial fibrillation in women is associated with increased risk for stroke, longer hospitalization, and extended care facility admission.