Abstract: In a method for determining DNA damage, wherein cells are treated with genotoxic agents and lysed and DNA fragments of the cells are separated according to their length by a physical separating method, cells are put into various chambers of a multi-chamber plate and a genotoxic chemicals are put into the various chambers of the multi-chamber plate. The cytotoxicity is then measured and the walls of the multi-chamber plate are then removed and the physical separation process is carried out together for all samples. The multi-chamber plate has removable walls and at least one coating in the bottom region. Samples for testing for DNA damage can be investigated especially quickly, effectively and inexpensively by the method using the coated multi-chamber plate.