Two patients with previously treated CLL received autologous PBSC transplantation after total body irradiation and high-dose chemotherapy. Before intensification, a partial marrow response had been obtained in both patients, with disappearance of peripheral blood involvement as shown by immunophenotypic assessment using fludarabine. PBSC collection was performed after a single course of high-dose cyclophosphamide followed by GM-CSF administration. One patient failed to reconstitute normal hematopoiesis and died 3 months post-transplant. The other is in continuous complete remission 12 months after intensification. This strategy in young patients with poor prognosis CLL warrants further investigation.