Cayman’s CFSE Cell Division Assay Kit provides an easy-to-use format for labeling and tracing cells through successive cell divisions. Carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE) diffuses into cells, where the acetate groups are cleaved to yield a highly fluorescent derivative (CFSE) that is retained in the cell and can be detected by flow cytometry. Cell division results in sequential halving of fluorescence, and up to eight divisions can be monitored before the fluorescence is decreased to the background fluorescence of unstained cells. The ease of use and lack of cytotoxicity allows monitoring of cellular division over weeks either in vitro or in vivo. The kit contains sufficient reagents for labeling and analyzing up to 7.5x108 cells by flow cytometry. CFSE-labeled cells can be further stained with any fluorochrome compatible with fluorescein for use in flow cytometry.