Systemic lupus erythematosus (SLE) is a disease of multifactorial etiology. Quantifying the burden of SLE across different countries can clarify the role of genetic, environmental and other causative factors in the natural history of the disease, and to understand its clinical and societal consequences. The aim of this study is to summarize data on SLE incidence and prevalence in the USA, Europe, Asia, and Australia. An extensive review of electronic resources (PubMed and MedLine) and medical journals was conducted to identify published studies on SLE incidence and prevalence over the period of 1950-early 2006. Researchers in the countries of interest provided additional information on the epidemiology of SLE. The incidence and prevalence of SLE varies considerably across the countries. The burden of the disease is considerably elevated among non-white racial groups. There is a trend towards higher incidence and prevalence of SLE in Europe and Australia compared to the U.S.A. In Europe, the highest prevalence was reported in Sweden, Iceland and Spain. There are marked disparities in SLE rates worldwide. This variability may reflect true differences across populations, or result from methodological differences of studies. The true geographic, racial, and temporal differences in SLE incidence and prevalence may yield important clues to the etiology of disease.