High dose therapy and stem cell transplantation is increasingly being used for treatment of CLL. The present article summarizes available results reported in literature on the use of high dose therapy followed by allogeneic or autologous hemopoietic precursor infusion. Transplant procedures seem a feasible approach, especially autografts, while allogeneic transplant has been associated with a higher mortality rate. Interesting clinical/biological results have been reported for both allogeneic and autologous transplants but prospective large clinical trials are needed to establish their real value. We consider important issues of stem cell transplantation in CLL patients, such as the kind of transplant (allogeneic vs autologous), the optimum timing, the selection of patients, the value and type of purging and, above all, impact on survival.