A workshop held by the "Groupe Français de Cytogénétique Hématologique" has identified a t(10;11)(p13-14;q14-21) in four acute lymphoblastic leukemias of T-cell lineage. The immunophenotypes were consistent with immature thymocytes. This translocation is therefore a new candidate for a recurrent translocation in early T-cell leukemia. A similar translocation has been reported as a rare change in early pre-B lymphoid leukemias and also in myeloid leukemias. It is not known whether the similar cytogenetic changes involve different molecular breakpoints or whether the same rearrangement affects a multipotential stem cell capable of lymphoid and myeloid differentiation.