Objective： To investigate the correlation between atrial tissue aldosterone level and atrial extracellular matrix remodeling in patients with atrial fibrillation and to evaluate the effects of aldosterone on the progress of atrial structural remodeling. Methods： Twenty-five patients with rheumatic heart valve disease （12 with sinus rhythm, 13 with chronic atrial fibrillation for ~6 months） were included in the present study. The right and left atrial lateral wall tissue samples（ 12 right and 7 left atrial samples in patients with sinus rhythm; 13 right and 8 left atrial samples in patients with atrial fibrillation）were obtained during mitral/aortic valve replacement operation. Radioimmunoassay was used to determine aldosterone level in local atria. Type Ⅰ or Ⅲ collagen volume fraction （CVF- Ⅰ or CVF-Ⅲ ） and total collagen volume fraction （CVF） were analyzed by immunohistochemistry and VG staining, respectively. Results： The left atrial diameters increased markedly in the atrial fibrillation group as compared to those in the sinus rhythm group（P〈.0. 01）. Aldosterone level, CVF-Ⅰ , CVF-Ⅰ/CVF-Ⅲ ratio, and total CVF in atrial fibrillation group were also increased significantly than those of sinus rhythm group（P〈0.01）, whereas CVF-Ⅲ remained compatible in the 2 groups. Aldosterone level, CVF- Ⅰ , CVF-Ⅰ/CVF-Ⅲ ratio, and total CVF were similar between the left atria and right atria in both groups. It was found that CVF-Ⅰ was positively correlated with the left atrial dimension （r=0. 856, P〈0. 001）, CVF was positively correlated with left atrial dimension（r=0. 845, P〈.0. 001）, and CVF-Ⅰ/CVF-Ⅲ ratio was positively correlated with atrial fibrillation duration（r=0. 766, P〈0.01）. Aldosterone level in local atria was also positively correlated with left atrial dimension （r= 0. 814, P〈0. 001） and CVF （r = 0. 885, P〈0. 001）. Conclusion： Local atria aldosterone level may promote the process of atrial structural remodeling in patients with atrial fibrillation and may also participate in the development and persistence of atrial fibrillation.