Ongoing studies in B-cell chronic lymphocytic leukemia are evaluating autologous peripheral blood stem cell (PBSC) transplantation in first remission following fludarabine therapy. However, fludarabine could impair PBSC harvest. In 38 patients after frontline oral fludarabine and cyclophosphamide (FDR-CY) therapy, we prospectively evaluated steady state filgrastim- or lenograstim-primed PBSC mobilization to collect 2.0 x 106/kg or more CD34 cells. The first mobilization, performed a median of 178 days (range, 69-377 days) from the last FDR-CY course, was unsuccessful in 32 patients. This result was significantly associated with a low platelet count before mobilization but not with age, interval from last FDR-CY course, initial stage, remission status, or other blood parameters. Finally, after 1, 2, and 3 mobilizations in 27, 10, and 1 patients, 2.0 x 106/kg or more CD34 cells were collected in only 12. Explorations of the mechanism of poor mobilization and adaptation of PBSC harvest policies after fludarabine treatment are therefore warranted.