Environmental, genetic, and ethnic factors seem to be involved in the expression of systemic lupus erythematosus (SLE). It has been reported that SLE in the Spanish-heritage population is more common and severe than in the white population in the United States. Data on the population with SLE in South America are scarce, however. The survival of 218 Chilean patients with SLE was studied. General features of the disease were similar to those in most reports. Survival at 10 years was 79%. Prognostic factors (P < .01) were the clinical markers of renal severity, including clinical stratification of renal disease, SLE disease activity index, thrombocytopenia, thromboembolism, and the use of "megadose" corticosteroids. Multivariate analysis suggested that the disease activity index had the strongest association with outcome (P = .0007); thrombocytopenia added a marginal risk (P = .04). Renal histology was analyzed in 127 patients. Risk factors for survival were clinical renal stage, elevated serum creatinine levels, and high activity index. Chronicity index was not a risk factor. Survival curves for World Health Organization types II and III were better than for type IV (P = .06). Multivariate analysis showed that creatinine levels correlated inversely with outcome (P = .0363). Disease expression of Chilean patients with SLE was similar to that in most reports. Survival was somewhat lower than in developed countries, which may be attributable to socioeconomic and racial factors.