We studied granulocyte colony-stimulating factor (G-CSF) mediated peripheral blood progenitor cells (PBPC), which were mobilized and collected from healthy donors for allogeneic transplantation. A total of 26 donors, age ranged from 21-41 years were mobilized with G-CSF at a dose of 7.5 microg/kg/day subcutaneously for 5 days and the collection was started on day 5. The CD34 cell counts reached a maximum on day 5 and subsequently declined despite continually given G-CSF. White blood cells (WBC), absolute neutrophil counts (ANC), absolute lymphocytes (AL) and their subsets, absolute mononuclear cells (AMNC), colony-forming unit-granulocyte, macrophage (CFU-GM) and CD34+ cells were increased about 6, 9, 2, 3, 34 and 40-fold, respectively, but red blood cells (RBC), hematocrit (Hct) and platelets (Pit) decreased on day 5 when compared to day 0. All parameters decreased after stem cell collection. For stem cell collection by Cobe Spectra, we used a blood volume of 19.27 +/- 4.65 liters, flow rate of 60.53 +/- 10.03 ml/minute, acid citrate dextrose solution (ACD)/blood ratio of 1:13.31, the final product volume was 314.14 +/- 72.24 ml, collection time was 325.40 +/- 73.36 minutes and one or two procedures were sufficient. The correlation between the number of CD34+ cells/kg, CFU-GM/kg and MNC/kg found in the harvested product and CD34 cells can be used for determining the necessary amount of progenitor cells for transplantation.