Cell assays include all methods of measurements on living cells. Confined for a long time to research laboratories, these emerging methods have, in recent years, found industrial applications that are increasingly varied and, from now on, regulatory. Based on the recent explosion of knowledge in cell biology, the measurement of living cells represents a new class of industry-oriented research tests, the applications of which continue to multiply (pharmaceuticals, cosmetics, environment, etc.). Cellular tests are now being positioned as new tools at the interface between chemical methods, which are often obsolete and not very informative, and methods using animal models, which are expensive, do not fit with human data and are widely discussed from an ethical perspective. Finally, the development of cell assays is currently being strengthened by their being put into regulatory application, particularly in Europe through the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) and cosmetic directives.