Lupus is one disease in which sex hormones and gender are quite important. Studies of autoimmune diseases like lupus have made the hormone connection more important and increased our overall understanding of the sexual dimorphism of the immune system. It is clear that some fundamental biologic mechanism is at work here and that only knowledge of the molecular mechanisms behind the action of the hormones can help us to understand the gender preference in this illness. Hormones may be potent regulators of cytokine levels and, consequently, disease activity.