Acute lymphoblastic leukemia of T cell lineage (T-ALL) is an aggressive malignant disease which accounts for 15 % of childhood ALL. T(11;14) is the more frequent chromosomal abnormality in childhood T-ALL, but its prognostic value remained controversial. Our aim was to analyze the outcome of childhood T-ALL with t(11;14) to know if the presence of this translocation is associated with a poor prognosis. We conducted a retrospective study from a series of 20 patients with t(11;14), treated in two consecutive trials from the European Organization for Research and Treatment of Cancer Children Leukemia Group over a 19-year period from 1989 to 2008. There were no significant differences between the 2 consecutive groups of patients with t(11;14) regarding the clinical and biological features at diagnosis. Among 19 patients who reached complete remission, 9 patients relapsed. We noticed 7 deaths all relapse- or failure-related. In the 58881 study, a presence of t(11;14) was associated with a poor outcome with an event-free survival at 5 years at 22.2 % versus 65.1 % for the non-t(11;14) T-ALL (p = 0.0004). In the more recent protocol, the outcome of T-ALL with t(11;14) reached that of non-t(11;14) T-ALL with an event-free survival at 5 years at 65.5 versus 74.9 % (p = 0.93). The presence of t(11;14) appeared as a poor prognostic feature in the 58881 trial whereas this abnormality no longer affected the outcome in the 58951 study. This difference is probably explained by the more intensive chemotherapy in the latest trial.