Peripheral blood progenitor cell (PBPC) components are being collected from healthy donors for allogeneic transplantation, but the quantity, quality, composition, and variability of PBPCs collected from healthy people given granulocyte‐colony‐stimulating factor (G‐CSF) have not been evaluated. PBPC components were collected from 150 healthy people who were given G‐CSF (5, 7.5, or 10 microg/kg/day) for 5 days. The components were evaluated for white cell (WBC), mononuclear cell, CD34+ cell, neutrophil, platelet, and red cell (RBC) composition. The quantities collected were: WBCs, 35.0 +/− 16.4 × 10(9) (range, 11.9–163.3 × 10(9)); mononuclear cells, 33.3 +/− 14.4 × 10(9) (range, 11.9–139.6 × 10(9)); CD34+ cells, 412 +/− 287 × 10(6) (range, 70–1658 × 10(6)); neutrophils, 1.71 +/− 3.59 × 10(9) (range, 0–27.6 × 10(9)); RBCs, 7.2 +/− 4.0 mL (range, 0–22.1 mL); and platelets, 480 +/− 110 × 10(9) (range, 250–920 × 10(9)). PBPC components collected from people given G‐CSF at 7.5 or 10 microg per kg per day contained significantly more CD34+ cells (respectively, 428 +/− 300 × 10(6); range, 70–1658 × 10(6) and 452 +/− 294 × 10(6); range, 78‐ 1380 × 10(6)) than those from people given G‐CSF at 5 microg per kg per day (276 +/− 186 × 10(6); range, 91–767 × 10(6)) (p = 0.007 and p = 0.002). When 10 microg per kg per day of G‐CSF was given, 50 percent of the components contained enough CD34+ cells for transplantation to a 75‐ kg recipient (375 × 10(6) CD34+ cells), but 10.6 percent of the components contained less than 150 × 10(6) CD34+ cells and thus would provide a transplantable dose only for a 30‐kg patient. One PBPC component collected from a healthy donor given 7.5 or 10 microg per kg per day of G‐CSF should contain 70 to 1660 × 10(6) CD34+ cells, with 0 to 22 mL of RBCs. Because of the great variability in the number of CD34+ cells collected, the quantity of CD34+ cells in each component should be measured after each procedure to ensure that sufficient quantities of cells are present for a successful transplant.