Rearrangements of JAK2 are rare and have been described in various hematological neoplasms. We report a novel JAK2 rearrangement resulting from a t(9;22)(p24;q11.2) in a 14-year-old male with a diagnosis of B lymphoblastic leukemia. He was treated with Children's Oncology Group's protocol (AALL0232) but failed to achieve remission by day 29. He underwent a second induction and entered remission. His clinical course suggested that this JAK2 rearrangement might portend an unfavorable prognosis. This case brings the total number of JAK2 rearranged lymphoblastic leukemia cases in the literature to seven. The molecular genetic and clinicopathologic features of these cases were reviewed. © 2010 Elsevier Ltd.