Acute leukemia is an untoward event following immunosuppression for solid organ transplantation and is related to the oncogenic effects of Epstein-Barr viral infections. The authors report a case of acute, Philadelphia chromosome-positive, T-cell lymphoblastic leukemia following liver transplantation. Molecular typing demonstrated a minor bcr-abl rearrangement (190 kD), which persisted in remission in 71% of peripheral neutrophils as determined by fluorescence in situ hybridization. The authors conclude that this patient may have presented in a lymphoid blast crisis of chronic myelogenous leukemia with an acute T-cell leukemia/lymphoma syndrome.