['Some studies have reported that serum CA125 level is elevated in SLE patients, and elevated CA125 level may be associated with kidney involvement and disease activity in SLE. However, none of the previous studies controlled confounding variables and the results remained controversial. The present study was aimed to investigate whether elevated serum CA125 level is independently associated with clinical and laboratory features of SLE by excluding various confounders in Chinese patients.', 'A total of 156 SLE patients, consisting of 139 women and 17 men, were included in the study. Some clinical and laboratory characteristics of the patients were obtained by medical record review. Serum CA125 levels were measured by electrochemiluminescence immunoassays.', 'Compared with patients with normal CA125, those with elevated CA125 had significantly more serositis (37.5% vs. 1.9%, p<0.001) and lung involvement (37.5% vs. 12%, p=<0.001), higher SLEDAI scores (p<0.007). Furthermore, disease duration was significantly longer in those with elevated CA125. Univariate logistic regression analysis showed that elevated serum CA125 level was closely associated with disease duration (OR, 95%CI:1.005, 1.001-1.010; p=0.014), serositis (OR, 95%CI: 32.258, 6.993-142.857; p<0.001), renal involvement (OR, 95%CI: 2.283, 1.114-4.673; p=0.024), lung involvement (OR, 95%CI: 4.386, 1.927-10.000; p<0.001) and SLEDAI scores (OR, 95%CI: 1.098, 1.027-1.174; p=0.006). After controlling for various confounding variables, serositis and disease duration were the only two clinical variables significantly associated with elevation of serum CA125 level. The best cut-off value for CA125 using the ROC curve was 38 kU/L (sensitivity 85%, specificity 75%) and the area under the ROC curve was 0.777 with 95%CI of 0.685-0.868 (p<0.001). Furthermore, the serum CA125 levels can fall into the normal range again with the improvement of serositis.'] Is serum CA125 elevation independently associated with serositis in SLE patients?