AIM: To determine and contrast the socioeconomic-demographic and clinical features of patients with recent onset (< or =5 y) systemic lupus erythematosus (SLE) from three ethnic groups, Hispanic, African-American and Caucasian (H, AA, C). SUBJECTS AND METHODS: SLE cases (American College of Rheumatology criteria) (incident (n = 56), prevalent (n = 173)), were enrolled in a longitudinal study at The University of Alabama at Birmingham, The University of Texas-Houston Health Science Center and The University of Texas Medical Branch at Galveston. Socioeconomic-demographic, clinical, immunological, behavioral and psychological data were obtained using validated instruments and standard laboratory techniques, and compared. RESULTS: 70 H, 88 AA and 71 C SLE patients constitute this cohort. H and AA patients were younger and of lower socioeconomic-demographic status. They also had evidence of more frequent organ system involvement (renal, cardiovascular), more auto-antibodies, more active disease (after adjusting for discrepant socioeconomic-demographic features), lower levels of social support and more abnormal illness-related behaviors (more in H than in AA). H also were more likely to have an abrupt disease onset; C were more likely to be on antimalarials but less likely to be on corticosteroids. H, AA, and C used health care resources comparably. They had similar levels of pain and physical and mental functioning after adjusting for age, disease duration, income, education, social support, illness-related behaviors, and Systemic Lupus Activity Measure or SLAM scores. CONCLUSIONS: H and AA patients have more active SLE, at an earlier age of onset, and a less favorable socioeconomic-demographic structure (worse among the H than AA) which predispose them to a less favorable natural history.