Two Arab children from the Gaza strip presented with fever, weakness, hepatosplenomegaly, lymphadenopathy and leukocytosis. The peripheral and bone marrow blasts had an immunophenotype compatable with T-cell acute lymphoblastic leukemia, and exhibited unusual markers (CD2+, CD3+, CD4-, CD8-). Cytogenetic studies revealed t(8;14)(q24;q11), possibly involving the alpha/delta locus of the T-cell receptor gene on chromosome 14 rather than the immunoglobulin heavy-chain locus usually involved in the t(8;14)(q24;q32), which is typical for Burkitt's leukemia/lymphoma. One of the children had a brother who died of T-cell acute lymphoblastic leukemia a few years later, however, his blasts showed deletion of chromosome 12. The possible role for environmental factors associated with low socioeconomic status, as well as of genetic factors in leukemogenesis are discussed.