Objective. Venous thrombosis is a relatively frequent and serious complication in systemic lupus erythematosus (SLE) that has been associated with the presence of antiphospholipid antibodies (aPL). However, venous thrombotic events can also be seen in patients without aPL, and only a few patients with aPL develop venous thrombosis. This study was carried out to ascertain other factors contributing to the development of venous thrombosis in SLE. Methods. Patients with SLE, ages ≥16 years with ≤5 years disease duration and of Hispanic, African American, or Caucasian ethnicity, from LUMINA (LUpus in Minorities, NAture versus nurture), a multiethnic, longitudinal study of outcome, were studied. Selected socioeconomic/demographic, clinical, laboratory, and treatment-exposure variables were compared between patients who developed and those who did not develop venous thrombotic events. Significant and clinically relevant variables were then entered into different multivariable models (Cox proportional hazards and unconditional stepwise logistic regression) to identify independent risk factors associated with the primary outcome. In another model, only patients who developed an event after enrollment (time 0) in the cohort were included. Results. Of 570 LUMINA patients, 51 developed at least 1 venous thrombotic event after SLE diagnosis. In univariable analyses, smoking (P = 0.020), shorter disease duration at time 0 (P = 0.017), serum levels of total cholesterol, low-density lipoprotein, and triglycerides (all P < 0.0001), and presence of lupus anticoagulant (LAC) (P = 0.045) were associated with venous thrombotic events. Survival analyses showed a time-dependent significant association of the primary outcome with smoking (P = 0.008) and a borderline significant association with the presence of LAC (P = 0.070). Multivariable models showed an independent association with smoking, age at time 0, disease activity over time, LAC, mean dose of glucocorticoids, and shorter disease duration at time 0. Conclusion. Venous thrombotic events occur early in the course of SLE. Our data confirm the association between LAC and venous thrombotic events. Smoking, shorter disease duration, older age, disease activity over time, and higher mean daily glucocorticoid dose were identified as additional risk factors for the development of this vascular complication. These findings may have implications for the management of patients with SLE. © 2005, American College of Rheumatology.