During the past 50 years, systemic lupus erythematosus (SLE) has been the main subject in the field of immunopathology. Each individual discovery was followed by the discovery of a multitude of related immune phenomena. This book reflects the present status of our understanding of this protean disease. Various animal models clearly show that different gene combinations can lead to the final clinical expression of SLE, with HLA class II genes probably responsible for the targeting of the autoimmune response. Similarly, research on cytokines in SLE patients has shown that SLE is a syndrome depending on different pathways. Finally, the question of prognosis is discussed. Fortunately, with every passing decade, the prognosis for patients with SLE gets better and better.