The Sysmex KX-21 is an automatic multi-parameter blood cell counter for in vitro diagnostic use in clinical laboratories. The KX-21 processes approximately 60 samples an hour and displays on the LCD screen the particle distribution curves of WBC, RBC, and platelets, along with data of 18 parameters, as the analysis results. Chapter 1 introduces the overview of the instrument, analysis procedure, etc. that we recommend you to read before using the KX-21.