BlueScreen HC uses a single cell strain, which permits 8 compounds to be tested across 8 dilutions (2-fold serial), together with untreated and positive controls, in one 96-well microplate. After arraying test compounds and dilutions, growing cells are added to each well. For studies without S9 metabolic activation data are collected after incubation (48h) using a multimode microplate reader. For studies incorporating S9 metabolic activation, cells are washed after a 3h incubation with test compound and S9. Measurements are made by microplate reader after a further 45h incubation period. Simple software gives automated decisions and a clear graphical output, including a complimentary indication of cytotoxicity (RCD).