This document specifies definitions and general requirements for cell viability analytical methods. It provides general considerations for selecting and establishing fit-for-purpose cell viability analytical methods. It also provides considerations for managing sources of variability for cell viability measurements during pre-analytical, analytical, and post-analytical phases. This document is applicable to cells in suspension, cells adhered to a substrate, and cells in complex matrices. This document is primarily applicable to cell viability measurements of nucleated mammalian cells. Several sector/application-specific international and national standards for cell viability currently exist. When applicable, the user can consult existing standards when operating with their scope.