Idiopathic thrombocytopenic purpura (ITP) is a common bleeding disorder in children and it is caused by autoantibodies against platelet surface antigens. Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that can affect any part of the body and so result in diverse clinical and laboratory manifestations, including thrombocytopenia. It is known that only 10∼15% of all SLE cases are diagnosed during childhood. Thrombocytopenia may be the sole manifestation early in the course of SLE, whereas SLE can subsequently develop in 1∼5% of ITP patients. We report here on an interesting case of SLE that developed in an eleven year-old girl with chronic and refractory ITP and who underwent splenectomy. (Korean J Dermatol 2010;48(11):1024∼1026)