Objective To explore link of change of plasma C-reactive protein (CRP) and atrial fibrillation (AF). Method The hsCRP enzyme-linked immunosorbent assay (ELISA) methods were used to measure plasma CRP levels in 21 patients with lone paroxysmal AF (LPAF) during AF and 7 days after return to sinus rhythm ;28 patients with lone sustained atrial fibrillation(LSAF) and 27 patients with rheumatic heart disease and chronic AF(RHD).Levels of plasma CRP were compared to levels in 32 patients with paroxysmal supraventricular tachycardia(PSVT) and 20 voluntary healthy subjects. Results Patients with LPAF,LPAF and RHD had high levels of CRP when compared with PSVT and the healthy subjects.No significant changes of CRP levels were found between the onset AF patients and those after 7 days of recovery.Patients with lone persistent AF and rheumatic heart disease with persistent AF had higher levels of CRP than those with LPAF,but have no significance.There were positive correlation between the duration of AF and the levels of CRP.But there were no relation with left atrial size on echocardiography,sex and ages. Conclusion These results indicate that elevated CRP levels in AF patients may play an important role in the occurrence and sustainment of AF.