Lymphoproliferative disorders (LPD) are reported with a much lower frequency in children with rheumatic diseases than in their adult counterparts. We describe 2 patients who developed a lymphoma during the course of the disease. The first is a 16-year-old girl diagnosed with systemic juvenile idiopathic arthritis 6 years before who developed a mucosa-associated lymphoid tissue (MALT) lymphoma. The second report involves a boy diagnosed with systemic lupus erythematosus at 9 years of age who developed a Hodgkin's lymphoma 9 years after the disease onset. In spite of the low frequency of LPD in children with rheumatic diseases, these processes do occur.