Peripheral blood stem cells (PBSC) are used for transplantation to reconstitute the hematopoietic system after high‐dose chemotherapy. PBSC are harvested from peripheral blood upon successful mobilization by cytokines and/or chemotherapy. Further in vitro manipulation steps like enrichment of CD34⁺ PBSC or gene transfer can be performed. To ensure the quality and safety of the final cell preparations intended for transplantation, national and international guidelines and regulations have been issued. Herein the implementation of a quality assurance program including the principles of good manufacturing practice (GMP) and a quality control (QC) system is one major concern. GMP regulations apply to all phases of cell collection, processing and storage as well as documentation, training of personnel, and the laboratory facility. QC measures have to be taken to ensure consistent quality and safety with an emphasis on preventing any deficiencies. Stem Cells 1997; 15(suppl 1): 275‐280