Objective: To investigate the factors affecting the efficiency of mobilization and collection of peripheral hematopoietic stem cells in acute leukemia patients.Methods: After mobilization with granulocyte colonystimulating factor (G-CSF) or with combined G-CSF and chemotherapy for acute leukemia patients, peripheral blood hematopoietic stem cells were collected using a CS 3000 PLUS blood cell separator.The effect of different diseases, method of mobilization, age, and sex on mobilization and collection were analyzed.WBC counts, morphological classification and CD34+detection were performed on the peripheral blood stem cells andthe peripheral blood before collection of the stem cells.