Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with manifold clinical manifestations and immunological abnormalities, affecting primarily women. Although accurate current data on its incidence and prevalence are largely lacking, there are numerous indications that SLE is far less common in Europeans and their descendants compared to all other ethnicities. The clinical manifestations of the disease show geographic or ethnic variation, generally being less severe in patients of European ancestry than in African, Asian, certain "Hispanic" or mestizo, and various indigenous populations. In particular, renal involvement is far more common in non-European patients. Genetic as well as environmental, sociodemographic and sociocultural factors are likely to contribute to the differences in the incidence and clinical expression of SLE.