Background: The B cell Activating Factor (BAFF) is implicated as a key cytokine in autoimmune precancerous disease Systemic Lupus Erythematosus, SLE. The objective of the work was to determine how glucocorticoids (GCs) treatment applied in SLE patients affects serum BAFF levels. The described study is the first one to consider this therapeutical internship. Methodology: The study was performed in two groups: 1 - GCs treatment (21 patients); 2 - conventional treatment (8 patients). The first group was divided into three subgroups, according to the dose of GCs: <10.0 mg/day, 10.0-49.0 mg/day and \(\ge\)50.0 mg/day). The BAFF measurement in blood was done using the ELISA method. Data were analyzed with descriptive statistical techniques, depending on the type of variable, and the Mann-Whitney inference test. Results: BAFF values were higher in patients with GCs \(\ge\) 50.0 mg/day, with a mean of 2,844 pg/ml ± 1,495. In patients receiving GCs <50.0 mg/day, the mean was 2,422 ± 1,280. The mean BAFF in patients receiving GCs was 2,482 pg/ml and in the control group 0.990 pg/ml. The difference between these two averages is statistically significant, using the non-parametric Mann-Whitney test, with p <0.001. GCs therapy is associated with an increase in serum BAFF levels using higher doses of GCs. Conclusion: The evaluation of serum BAFF level in SLE treatment has become the potential new biomarker of GCs therapy. The presented results constitute a novel contribution to the diagnosis and therapy of SLE.