Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder that disproportionally affects women, especially in their reproductive years. SLE is associated with considerable pregnancy-related morbidity--including fetal loss, preterm birth, fetal growth restriction and pre-eclampsia. CD4+CD25+ regulatory T (T(REG)) cells have a potent immunosuppressive function and contribute to immunological self-tolerance. These cells might be essential for successful placental development by ensuring fetal tolerance. The numbers of T(REG) cells are augmented during normal pregnancy and, conversely, diminished numbers are associated with pregnancy loss and pre-eclampsia. Several studies have shown that patients with SLE have decreased numbers of T(REG) cells that might be functionally defective. This defective T(REG) cell functioning could predispose women with SLE to pregnancy complications. This article provides an overview of current knowledge of the role and function of T(REG) cells in SLE and pregnancy and how these cells might contribute to improving pregnancy-related outcomes in patients with SLE in the future.