Summary:Chronic lymphocytic leukaemia is a condition which has a median age of 65 years but approximately 10% of patients are younger than 50. Fludarabine has been shown to produce better response rates than conventional single agent or combination chemotherapy but as yet no improved survival. We have treated a series of 10 patients presenting with de novo (six) or relapsed (four) chronic lymphocytic leukaemia (CLL) with fludarabine as cytoreduction treatment and consolidation of the response with CD34 selected peripheral blood stem cell transplantation using cyclophosphamide and total body irradiation (TBI) as conditioning therapy. We report here on the progenitor cell harvest characteristics and clinical and molecular responses to both fludarabine and high-dose consolidation. Our results indicate that at 3 months post transplant clinical remissions were induced in 10/10 patients and molecular responses in 7/8 (88%) evaluable patients. Molecular relapses occurred on long-term follow-up at 6, 9, 12 and 24 months post transplant but patients continued in clinical and haematological remission. Two patients have died from progressive disease and a third patient from aggressive high grade lymphoma. Median survival from the time of transplantation for the group overall was 22 months (range 6-45). There was no procedure-related mortality in the first 100 days. Keywords: autologous blood cell transplantation; molecular responses; multiple myeloma Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in people over 50 years old with a median age at presentation of 64 years. It is, however, being seen in an increasing number of patients under this age and data from the South East Thames Malignancy Register suggests that it has an incidence in the under 50s of approximately 1:350 000. Median overall survival varies according to stage but the range is extremely wide. However, the influence of the disease on survival is similar regardless of age. 1 Furthermore, although initial response rates are in the region of 80% median response duration is only 2 years. 2 Recently a new purine analogue, fludarabine, has been