The exact aetio-pathogenesis of systemic lupus erythematosus (SLE) is still speculative, where dysregulation or depletion of CD4+CD25+ T lymphocytes is among the supposed mechanisms. In this study, we thought to investigate patients with SLE for percentages of CD4+CD25+ T cells in their peripheral blood and to correlate this with their disease activity scores. Twenty-five patients with SLE who fulfilled, at least, four of the revised Criteria of the American College of Rheumatology (ACR) and twenty healthy volunteers participated in this study. Activity of SLE was assessed by SLE disease activity index (SLEDAI) score. Percentages of CD4+CD25+ T-cells were determined by a flowcytometric technique, while recently activated T-cells were analysed by assaying the expression of the T-cell activation marker, CD69. A statistically significant (p = 0.003) reduction of percentage of CD4+CD25+ T cells was observed among patients (mean 7.16+/-4.53 %) when compared with control subjects (mean 11.36+/-4.50 %), while a non-significant (p = 0.475) low expression of CD69 on CD4+ T cells was observed between patients (mean 0.32+/-0.28 %) and control subjects (mean 0.32+/-0.38 %). In addition, no correlation could be detected between percentages of CD4+CD25+ T cells and SLEDAI scores among SLE patients (p=0.079). In conclusion, this study adds some evidence for the role of CD4+CD25+ T cells in the pathogenesis of SLE that may have some future therapeutic applications.