Onc of the most striking and potentially important observations in the epidemiology of systemic lupus erythematosus (SLE) is its apparent predilection for women of African origin (1-7). There may also be an increasing prevalence of lupus as one goes from Africa to North America and from Africa to Europe (we term this the “prevalence gradient hypothesis”)(2). If there were a gradient, it might provide insights into the pathogenesis and potential genetic and environmental factors that may be important in the cause of SLE and/or its prognosis. Such a finding might have the same significance as migrant studies of coronary artery disease among Japanese in Japan, Hawaii, and America, which provided the first clues that diet might be an important factor in coronary artery disease (8), or studies of the geographic differences in insulin-dependent diabetes mellitus, which have provided data on the interaction between genetic and environmental factors (9). In this analytical synthesis, we review the human and genetic epidemiology of SLE in populations of African ancestry. African Americans are defined herein