Williams-Beuren Syndrome (WBS) is associated with constitutional deletion of 7q11.23, which includes the elastin gene. Cytogenetic abnormalities of chromosome 7 are frequently described in several human malignancies. Here, we report Burkitt Leukemia in an 8-year-old boy with WBS. In this patient, constitutional deletion of chromosome 7q11.23 including BCL7B was confirmed. WBS may predispose patients to Burkitt Leukemia.