Ensuring safety of newly invented products, i.e. chemicals, pharmaceuticals, biocides, cosmetics, nanomaterials, should comprise a crucial part of their development. Toxicity testing relies from many years on animal models, which – however providing indisputable benefits – raises more and more ethical and scientific concerns. This challenge has driven an intensive search for alternative methods of toxicity testing, designed in line with 3R rule, advocating for replacement of animals, reduction of their number and constant refinement of available methods. As a result, many alternative methods have been developed and introduced to a routine toxicity testing. However, many of in vivo methods or endpoints still do not have an alternative and existing alternative methods not always give a reliable and reproducible results. Therefore the imperative of alternative toxicity testing development and improvement is still of great importance. Strengthening of research facilities and exchange of experience is the way to achieve this goal.