Objective: To determine the features associated with acute onset systemic lupus erythematosus (SLE). Methods: A total of 631 SLE patients from LUMINA (for "lupus in minority populations: nature vs nurture"), a multiethnic (Hispanics, African-Americans and Caucasians) cohort, were studied. Acute disease onset was defined as the accrual of ≥4 American College of Rheumatology (ACR) criteria for the classification of SLE in ≤4 weeks. Socioeconomic demographic features, clinical manifestations, disease activity, damage accrual, mortality, autoantibodies, HLA class II and FCGR alleles, behavioural/psychological variables were compared between patients with acute and insidious disease onset by univariable (χ2 and Student t test) and multivariable (stepwise logistic regression) analyses. Results: A total of 94 (15%) patients had acute disease onset. In the multivariable analysis, patients with acute onset lupus had more renal involvement (odds ratio (OR) = 1.845, 95% CI 1.076-3.162; p = 0.026) and higher disease activity (OR = 1.057, 95% CI 1.005-1.112; p = 0.030). By contrast, age (OR = 0.976, 95% CI 0.956-0.997; p = 0.025), education (OR = 0.901, 95% CI 0.827-0.983, p = 0.019), health insurance (OR = 0.423, 95% CI 0.249-0.718; p = 0.001) and skin involvement (OR = 0.346, 95% CI 0.142-0.843; p = 0.019) were negatively associated with acute onset lupus. No differences were found regarding the serological, genetic and behavioural/psychological features; this was also the case for damage accrual and mortality. Conclusions: Patients with acute onset lupus seem to be younger, have a lower socio-economic status and display more severe disease in terms of clinical manifestations and disease activity. However, intermediate (damage) and long-term (mortality) outcomes appear not to be influenced by the type of disease onset in SLE.