Clinical and laboratory manifestations and outcome of systemic lupus erythematosus (SLE) may vary in different populations. A prospective multinational inception cohort should prove useful in identifying the influence of ethnicity on the clinical characteristics of SLE. We therefore analyzed clinical, laboratory, and prognostic variables in Latin American SLE patients with disease of recent onset who were entered into a prospective cohort, and compared these variables in the cohort's 3 major ethnic groups. Thirty-four centers from 9 Latin American countries participated by randomly incorporating SLE patients within 2 years of diagnosis into a standardized database. Participating centers were selected for their expertise in diagnosing and managing SLE. We were then able to evaluate prospectively socioeconomic variables, ethnicity, type of medical care, clinical and laboratory features, disease activity, damage, and mortality at each site. A coordinating center controlled the quality of the information submitted. Of the 1,214 SLE patients included in the cohort, 537 were mestizos, 507 were white, and 152 were African-Latin American (ALA). (There were also small numbers of pure Amerindian and oriental individuals.) Significant differences were found between them in socioeconomic characteristics, type of care, and level of education favoring whites. Mestizos and ALA were younger at onset. Delay to diagnosis and disease duration was shorter in ALA. Fever was more frequent in whites; discoid lesions in ALA; renal disease and lymphopenia in mestizos and ALA. Although we found differences in background variables between ethnic groups from different countries, mestizos from 2 distant countries (Argentina and Mexico) were clinically akin and showed similar differences to whites. Mortality was associated with lower education, poor medical coverage, and shorter follow-up. In an exploratory model nonwhite ethnicity was associated with renal disease and lymphopenia, damage, and cumulative American College of Rheumatology criteria. These differences in clinical, prognostic, socioeconomic, educational, and access to medical care features in Latin American lupus patients of 3 major ethnic groups from 9 different countries may have an impact on the patients' disease. "Hispanics," as they have come to be generically termed on the basis of language, actually constitute a markedly heterogeneous group of subjects.