The identification of differences in the clinical manifestations of systemic lupus erythematosus (SLE) due to racial and socioeconomic factors has been hampered in previous studies by limitations in the numbers of black patients examined. We sought to define racial differences in the cumulative clinical manifestations of SLE in a large, racially balanced cohort (184 black patients and 174 white patients). Differences in the cumulative disease manifestations of SLE between black and white patients were evaluated by multivariate regression techniques, controlling for socioeconomic status and the potential confounding factors of age, gender, duration of follow-up, and treatments. Race was found to be an important factor influencing the prevalence of 9 of 24 clinical features of SLE. As a group, blacks more commonly manifested anti-Sm and anti-RNP antibodies, discoid skin lesions, and proteinuria, and less commonly manifested photosensitivity, than whites. Among specific age, gender, and socioeconomic subgroups, blacks were more likely than whites to have had psychosis, serositis, and urinary cellular casts, and less likely to have had sicca syndrome. Racial differences in the prevalence of renal failure were due to socioeconomic effects. These results suggest that race is under-recognized as a factor influencing the clinical heterogeneity of SLE.