Transient pancytopenia preceding acute lymphoblastic leukemia (pre-ALL) is a rare occurrence usually affecting children with subsequent development of B lineage ALL. We report a case of pre-ALL characterized by a T cell immunophenotype and abnormal karyotype t (11; 14) (q10; q10). The patient achieved a transient complete remission after initial therapy, but relapsed within a few months and died of leukemic encephalopathy. To the best of our knowledge, this is the first report of T lineage pre-ALL.