Multiple-parameter flow cytometric analysis for the expression of cell surface markers has been generally used in various clinical and fundamental fields. This was made possible by the development of many monoclonal antibodies and new fluorescence dyes coordinately with the progress in hardwares. Especially, the development of new fluorescence dyes enabled us simultaneously analysis of more than two markers, not only surface markers but also intracellular events, such as Ca2+ concentration and cell cycle. As a result, fine characterization of cells of interest is now possible even with a limited number of cells within a shorter time. The high resolution and sensitivity of current multiple-parameter flow cytometer make possible the isolation of diverse and unique cell populations that can be obtained by no other way.