The LIVE⁄DEAD® Fixable Dead Cell Stain Kit employs an amine-reactive fluorescent dye to evaluate mammalian cell viability by flow cytometry. In cells with compromised membranes, the dye reacts with free amines both in the cell interior and on the cell surface, yielding intense fluorescent staining. In contrast in viable cells, the dye's reactivity is restricted to the cell-surface amines, resulting in less intense fluorescence. The difference in intensity between the live and dead cell populations is typically greater than 50 fold, and this fluorescence intensity discrimination is completely preserved following formaldehyde fixation. The single-color assays use only one channel of a flow cytometer making the reactive dyes in the LIVE⁄DEAD® Fixable Dead Cell Stain Kits compatible with multiparameter staining experiments. The Sampler Kit contains a vial of reactive dye from all eight amine-reactive dyes with excitation ranging from UV-Far Red to maximize the flexibility in experimental design. Also available are the LIVE⁄DEAD® Fixable Dead Cell Stain Kits that contain blue-fluorescent dye (L-23105), green fluorescent dye (L-231010), violet fluorescent dye (L-34955), aqua fluorescent dye (L-34957), yellow fluorescent dye (L-34959), red fluorescent (L-23102), far-red fluorescent dye (L-10120), and near-IR fluorescent dye (L-10119).