In recent years, biological tests have been developed based on cell cultures and successfully used to the hygienic assess of a variety of samples. In vitro assays become the complement of conventional chemical methods. They do not narrow the results only to the quantitative and qualitative information on toxic substances, but also increase knowledge on the direct impact on the organism. They are also an alternative for animal testing, which are currently given up for ethical reasons. At present, the market is steadily increasing in the number of tests and bio-assay techniques. Based on our own studies we conclude that the MTT test is perfect as a diagnostic method for evaluating the cytotoxicity of materials of different composition such as mycotoxins, pesticides, bacterial cultures, moulds isolates, food, feed, as well as a vast spectrum of other environmental samples