To define in children with systemic lupus erythematosus (SLE) the incidence, outcome, and association of thrombocytopenia with other SLE manifestations, specifically thromboembolic events (TEs), we retrospectively reviewed 106 pediatric patients with SLE diagnosed between 1992 and 2001. Thrombocytopenia was found in 50%, which was of a moderate or severe degree in 34%. The thrombocytopenia was sustained in 29% of all patients. Twelve patients were diagnosed with autoimmune thrombocytopenic purpura 2 to 69 months before the diagnosis of SLE. Of them, 10 children required treatment, and three patients underwent splenectomy. TEs occurred in 10.4% of the total cohort of 106. Lupus anticoagulant, but not anticardiolipin antibodies and sustained thrombocytopenia, were associated with a higher risk for TEs.